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#LyX file created by tex2lyx 2.3 \lyxformat 544 \begin_document \begin_header \save_transient_properties true \origin /home/jhj/src/grg/ \textclass report \begin_preamble %==========================================================================% % GRG 3.2 Manual (C) 1988-97 Vadim V. Zhytnikov % %==========================================================================% % LaTeX 2e and MakeIndex are required to pront this document: % % % % latex grg32 % % latex grg32 % % latex grg32 % % makeindex grg32 % % latex grg32 % % % % If you do not have MakeIndex just omit two last steps. % % The document is intended for two-side printing. % %==========================================================================% \oddsidemargin=1.5cm \evensidemargin=1.3cm %%% This is for PS fonts and dvips driver %\usepackage{mathptm} %\usepackage{palatino} %\renewcommand{\bfdefault}{b} %\newcommand{\grgtt}{\bfseries\ttfamily} %\usepackage[dvips]{color} %\definecolor{shade}{gray}{.9} %\newcommand{\shadedbox}[1]{\fcolorbox{black}{shade}{#1}} %%% This is for CM fonts \newcommand{\grgtt}{\ttfamily} \newcommand{\shadedbox}[1]{\fbox{#1}} %%% %\usepackage{calrsfs} % rsfs for mathcal %%% \let\@afterindentfalse\@afterindenttrue \@afterindenttrue %%% %%% \usepackage{makeidx} \newcommand{\cmdind}[1]{\index{Commands!\comm{#1}}\index{#1@\comm{#1} (command)}} \newcommand{\cmdindx}[2]{\index{Commands!\comm{#1}}\index{#1@\comm{#1} (command)!\comm{#2}}} \newcommand{\swind}[1]{\index{Switches!\comm{#1}}% \index{#1@\comm{#1} (switch)}% \label{#1}} \newcommand{\swinda}[1]{\index{Switches!\comm{#1}}% \index{#1@\comm{#1} (switch)}} %%% %%% \newcommand{\rim}[1]{\stackrel{\scriptscriptstyle\{\}}{#1}\!} %%% %%% \newcommand{\object}[2]{% \begin{equation} \mbox{\comm{#1}} =\ #2 \end{equation}} \newcommand{\tsst}{\longleftrightarrow} \newcommand{\vv}{\vphantom{\rule{5mm}{5mm}}} \newcommand{\RR}[1]{\stackrel{\rm #1}{R}\!{}} \newcommand{\OO}[1]{\stackrel{\rm #1}{\Omega}\!{}} %%% %%% \newcommand{\ipr}{\rule{1.8mm}{.1mm}\rule{.1mm}{2.2mm}\,} % _| int. product %%% %%% \newcommand{\spref}[1]{section \ref{#1} on page \pageref{#1}} \newcommand{\pref}[1]{page \pageref{#1}} %%% %%% \newcommand{\seethis}[1]{\marginpar{\footnotesize\it #1}} \newcommand{\rseethis}[1]{ \reversemarginpar \marginpar{\footnotesize\it #1} \normalmarginpar} \newcommand{\important}[1]{\marginpar{\itshape\bfseries\fbox{\ !\ } #1}} %%% %%% Footnotes simbol ... \renewcommand{\thefootnote}{\fnsymbol{footnote}} % + ++ etc for footnotes \def\@fnsymbol#1{\ensuremath{\ifcase#1\or \dagger\or \ddagger\or \mathchar "278\or \mathchar "27B\or \|\or *\or **\or \dagger\dagger \or \ddagger\ddagger \else\@ctrerr\fi}} %%% %%% Page layout ... \textheight=180mm \textwidth=120mm %\marginparsep=2mm %\marginparwidth=28mm \marginparsep=5mm \marginparwidth=25mm \parindent=6mm \parskip=1.2mm plus 1mm minus 1mm %%% \newlength{\myparindent} \myparindent=\parindent %%% My own \tt font ... \def\verbatim@font{\grgtt} \renewcommand{\tt}{\grgtt} %%% %%% %%% Special symbols ... \def\^{{\tt \char'136}} %%% \^ is ^ \def\_{{\tt \char'137}} %%% \_ is _ \newcommand{\w}{{\tt \char'057 \char'134}} %%% \w is /\ \newcommand{\bs}{{\tt \char'134}} %%% \bs is \ \newcommand{\ul}{{\tt \char'137}} %%% \ul is _ \newcommand{\dd}{{\tt \char'043}} %%% \dd is # \newcommand{\cc}{{\tt \char'176}} %%% \cc is ~ \newcommand{\ip}{{\tt \char'137 \char'174}} %%% \ip is _| \newcommand{\ii}{{\tt \char'174}} %%% \ii is | \newcommand{\udr}{\mbox{$\Updownarrow$}} %%% %%% \grg GRG logo ... \newcommand{\grg}{{\sc GRG}} \newcommand{\reduce}{{\sc Reduce}} \newcommand{\maple}{{\sc Maple}} \newcommand{\macsyma}{{\sc Macsyma}} \newcommand{\mathematica}{{\sc Mathematica}} %%% \marg ... \newcommand{\marg}[1]{\marginpar{\tiny#1}} %%% \command{...} commands in (shaded) box \def\mynewline{\ifvmode \relax \else \unskip\nobreak\hfil\break\fi} \newcommand{\command}[1]{\vspace{1.2mm}\mynewline\hspace*{6mm}% \shadedbox{\begin{tabular}{l}\tt% #1 \end{tabular}}\vspace{1.2mm}\newline} %%% parts of the commands \newcommand{\file}[1]{{\sf#1}} \newcommand{\comm}[1]{{\upshape\tt#1}} % \comm short in-line command \newcommand{\parm}[1]{{\sf\slshape#1\/}} % \parm command parameter \newcommand{\opt}[1]{{\rm[}#1{\rm]}} % \opt optional part of command \newcommand{\user}[1]{{\bfseries\ttfamily#1}} % \user user input \newcommand{\rpt}[1]{#1{\rm[}{\tt,}#1{\rm\dots}{\rm]}} % \rpt repetition \def\closerule{\rule{.1mm}{1mm}\rule{119.8mm}{.1mm}} \def\openrule{\rule{.1mm}{1mm}\rule[1mm]{119.8mm}{.1mm}} %%% \begin{slisting} ... \end{slisting} small font listing with frame %%% \begin{listing} ... \end{listing} normal font listing without frame \newcommand{\etrivlistrule}{\vspace*{-3mm}\endtrivlist{\closerule}\newline} \newdimen\allttindent \allttindent=0mm \def\docspecials{\do\ \do\$\do\&% \do\#\do\^\do\^^K\do\_\do\^^A\do\%\do\~} \def\slisting{\vspace*{-2mm}% \trivlist \item[]\if@minipage\else\relax\fi \leftskip\@totalleftmargin \advance\leftskip\allttindent \rightskip\z@ \parindent\z@\parfillskip\@flushglue\parskip\z@ \@tempswafalse\openrule \def\par{\if@tempswa\hbox{}\fi\@tempswatrue\@@par} \obeylines \small\grgtt% \catcode``=13 \@noligs \let\do\@makeother \docspecials \frenchspacing\@vobeyspaces} \def\listing{\trivlist \item[]\if@minipage\else\relax\fi \leftskip\@totalleftmargin \advance\leftskip\allttindent \rightskip\z@ \parindent\z@\parfillskip\@flushglue\parskip\z@ \@tempswafalse \def\par{\if@tempswa\hbox{}\fi\@tempswatrue\@@par} \obeylines \grgtt% \catcode``=13 \@noligs \let\do\@makeother \docspecials \frenchspacing\@vobeyspaces} \let\endslisting=\etrivlistrule \let\endlisting=\endtrivlist %%% %%% Headings style ... %\usepackage{fancyheadings} %%% We just inserat the fancyheadings.sty here literally ... % fancyheadings.sty version 1.7 % Fancy headers and footers. % Piet van Oostrum, Dept of Computer Science, University of Utrecht % Padualaan 14, P.O. Box 80.089, 3508 TB Utrecht, The Netherlands % Telephone: +31-30-531806. piet@cs.ruu.nl (mcvax!sun4nl!ruuinf!piet) % Sep 16, 1994 % version 1.4: Correction for use with \reversemargin % Sep 29, 1994: % version 1.5: Added the \iftopfloat, \ifbotfloat and \iffloatpage commands % Oct 4, 1994: % version 1.6: Reset single spacing in headers/footers for use with % setspace.sty or doublespace.sty % Oct 4, 1994: % version 1.7: changed \let\@mkboth\markboth to % \def\@mkboth{\protect\markboth} to make it more robust \def\lhead{\@ifnextchar[{\@xlhead}{\@ylhead}} \def\@xlhead[#1]#2{\gdef\@elhead{#1}\gdef\@olhead{#2}} \def\@ylhead#1{\gdef\@elhead{#1}\gdef\@olhead{#1}} \def\chead{\@ifnextchar[{\@xchead}{\@ychead}} \def\@xchead[#1]#2{\gdef\@echead{#1}\gdef\@ochead{#2}} \def\@ychead#1{\gdef\@echead{#1}\gdef\@ochead{#1}} \def\rhead{\@ifnextchar[{\@xrhead}{\@yrhead}} \def\@xrhead[#1]#2{\gdef\@erhead{#1}\gdef\@orhead{#2}} \def\@yrhead#1{\gdef\@erhead{#1}\gdef\@orhead{#1}} 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\font_tt_scale 100 100 \use_microtype false \use_dash_ligatures true \graphics default \default_output_format default \output_sync 0 \bibtex_command default \index_command default \paperfontsize default \spacing single \use_hyperref false \papersize default \use_geometry false \use_package amsmath 1 \use_package amssymb 0 \use_package cancel 0 \use_package esint 1 \use_package mathdots 0 \use_package mathtools 0 \use_package mhchem 0 \use_package stackrel 0 \use_package stmaryrd 0 \use_package undertilde 0 \cite_engine basic \cite_engine_type default \biblio_style plain \use_bibtopic false \use_indices false \paperorientation portrait \suppress_date false \justification true \use_refstyle 0 \use_minted 0 \index Index \shortcut idx \color #008000 \end_index \secnumdepth 3 \tocdepth 3 \paragraph_separation indent \paragraph_indentation default \is_math_indent 0 \math_numbering_side default \quotes_style english \dynamic_quotes 0 \papercolumns 1 \papersides 2 \paperpagestyle fancy \tracking_changes false \output_changes false \html_math_output 0 \html_css_as_file 0 \html_be_strict false \end_header \begin_body \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{titlepage} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash hsize \end_layout \end_inset =150mm \begin_inset space \hrulefill{} \end_inset \begin_inset VSpace 20mm* \end_inset \end_layout \begin_layout Standard \align center \size giant \series bold GRG \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash \backslash [1mm] \end_layout \end_inset \size normal Version 3.2 \end_layout \begin_layout Standard \align center \series bold \size normal \size larger Computer Algebra System for \begin_inset Newline newline \end_inset Differential Geometry, \begin_inset Newline newline \end_inset Gravitation and \begin_inset Newline newline \end_inset Field Theory \begin_inset VSpace 25mm* \end_inset \begin_inset Newline newline \end_inset \shape italic Vadim V. Zhytnikov \size larger \begin_inset Newline newline \end_inset \begin_inset VSpace vfill \end_inset \size normal Moscow, 1992–1997 \begin_inset Formula $\bullet$ \end_inset Chung-Li, 1994 \size larger \end_layout \begin_layout Standard \series bold \size larger \begin_inset space \hrulefill{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{titlepage} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash setcounter{page}{0} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash thispagestyle{empty} \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset CommandInset toc LatexCommand tableofcontents \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash thispagestyle{empty} \end_layout \end_inset \end_layout \begin_layout Chapter Introduction \end_layout \begin_layout Standard Calculation of various geometrical and physical quantities and equations is the usual technical problem which permanently arises in geometry, field and gravity theory. Numerous indices, contractions and components make these calculations very tedious and error-prone. Since this calculus obeys the well defined rules the idea to automate this kind of problems using computer is quite natural. Now there are several computer algebra systems such as \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash maple \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mathematica \end_layout \end_inset \begin_inset space \space{} \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash macsyma \end_layout \end_inset \begin_inset space \space{} \end_inset which in principle allow one to do this and it is not so hard to write a program to calculate, for example, the curvature tensor or connection. But suppose that we want to make a non-trivial coordinate transformation or tetrad rotation, calculate covariant or Lie derivative, compute a complicated expression with numerous contraction or raise or lower some indices. All these operations are typical in differential geometry and field theory but their realization with the help of general purpose computer algebra systems requires hard programming since all these systems really know nothing about \emph on covariant properties \emph default of geometrical quantities. \end_layout \begin_layout Standard The computer algebra system \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is designed in such a way to make calculation in differential geometry and field theory as simple and natural as possible. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is based on the computer algebra system \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset but \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset has its own simple input language whose commands resembles English phrases. Working with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset no any knowledge of programming is required. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset understands tensors, spinors, vectors, differential forms and knows all standard operations with these quantities. Input form for mathematical expressions is very close to traditional mathematical notation including Einstein summation rule. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset knows the covariant properties of these objects, you can easily raise and lower indices, compute covariant and Lie derivatives, perform coordinate and frame transformations. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset works in any dimension and allows one to represent tensor quantities with respect to holonomic, orthogonal and even any other arbitrary frame. \end_layout \begin_layout Standard One of the useful features of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is that it has a large number of built-in standard field-theory and geometrical quantities and formulas for their computation. Thus \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset provides ready solutions to many standard problems. \end_layout \begin_layout Standard Another unique feature of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is that it can export results of calculations into other computer algebra system. You can save your data in to the file in the format of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash maple \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mathematica \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash macsyma \end_layout \end_inset \begin_inset space \space{} \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset in order to use this system to proceed analysis of the data. The \SpecialChar LaTeX \begin_inset space \space{} \end_inset output format is supported as well. In addition \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is compatible with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset graphics shells providing niece book-quality output with Greek letters, integral signs etc. \end_layout \begin_layout Standard The main built-in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset capabilities are: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{list} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset Formula $\bullet$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash labelwidth \end_layout \end_inset =8mm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash leftmargin \end_layout \end_inset =10mm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Connection, torsion and nonmetricity. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Curvature. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Spinorial formalism. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Irreducible decomposition of the curvature, torsion, and nonmetricity in any dimension. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Einstein equations. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Scalar field with minimal and non-minimal interaction. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Electromagnetic field. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Yang-Mills field. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Dirac spinor field. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Geodesic equation. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Null congruences and optical scalars. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Kinematics for time-like congruences. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Ideal and spin fluid. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Newman-Penrose formalism. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Gravitational equations for the theory with arbitrary gravitational Lagrangian in Riemann and Riemann-Cartan spaces. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{list} \end_layout \end_inset \end_layout \begin_layout Standard I would like to stress that current \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset version is intended for calculations in a concrete coordinate map only. It cannot operate with tensors as with objects having abstract symbolic indices. \end_layout \begin_layout Standard This book consist of two main parts. First part contains detailed description of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset as a programming system. Second part describes all built-in objects and formulas for their computation. \end_layout \begin_layout Chapter Programming in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \end_layout \begin_layout Standard Throughout the chapter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset commands \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are printed in typewriter font. The slanted serif-less font is used for command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset parameters \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The optional parts of the commands are enclosed in squared brackets \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset option \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset stands for one or several repetitions of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset : \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset etc. Examples are separated form the text by horizontal lines \begin_inset Formula $\stackrel{\rule{0.1mm}{1mm}\rule[1mm]{3mm}{0.1mm}} {\rule{0.1mm}{1mm}\rule{3mm}{0.1mm}}$ \end_inset and the user input can be easily distinguished from the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset output by the prompt \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset <- \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset which precedes every input line. \end_layout \begin_layout Section Session, Tasks and Commands \end_layout \begin_layout Standard To start \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset it is necessary to start \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset On some systems you have to use \family typewriter \shape up load!_package grg; \family default \series default \shape default \begin_inset Newline newline \end_inset since \family typewriter \shape up load \family default \series default \shape default is not defined. \begin_inset Newline newline \end_inset \begin_inset Newline newline \end_inset Sometimes it \begin_inset Newline newline \end_inset is better to use two commands \begin_inset Newline newline \end_inset \family typewriter \shape up load grg32; grg; \family default \series default \shape default \begin_inset Newline newline \end_inset or \begin_inset Newline newline \end_inset \family typewriter \shape up load grg; grg; \family default \series default \shape default \begin_inset Newline newline \end_inset (See section \begin_inset CommandInset ref LatexCommand ref reference "configsect" plural "false" caps "false" noprefix "false" \end_inset for details.) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset enter the command \family typewriter load grg; \family default \series default \shape default \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset REDUCE 3.5, 15 Oct 93, patched to 15 Jun 95 ... \end_layout \begin_layout Standard 1: load grg; \end_layout \begin_layout Standard This is GRG 3.2 release 2 (Feb 9, 1997) ... \end_layout \begin_layout Standard System directory: c: \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset reduce \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset grg32 \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset System variables are upper-cased: E I PI SIN ... Dimension is 4 with Signature (-,+,+,+) \end_layout \begin_layout Standard <- \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Symbol \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset <- \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset prompt which shows that now \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset waits for your input. The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset \emph on task \emph default (we prefer this term instead of usual \emph on program \emph default ) consist of the sequence of commands terminated by semicolon \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Reading the input \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset splits it on \emph on atoms \emph default . There are several types of atoms: \begin_inset Index idx status collapsed \begin_layout Plain Layout Atoms \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{list} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset Formula $\bullet$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash labelwidth \end_layout \end_inset =4mm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash leftmargin \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parindent \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset The identifier or symbol is a sequence of letters and digits starting with a letter: \end_layout \begin_layout Verbatim i I alpha1 beta ABC123D Find \end_layout \begin_layout Standard The identifiers in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset may have trailing tilde character \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset . Any other character may be incorporated in the identifier if preceded by the exclamation sign: \begin_inset Index idx status collapsed \begin_layout Plain Layout Identifiers \end_layout \end_inset \end_layout \begin_layout Verbatim beta~ LIMIT!+ \end_layout \begin_layout Standard The identifiers in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset play the role of the variables and functions in mathematical expressions and words in commands. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Integer numbers \begin_inset Index idx status collapsed \begin_layout Plain Layout Numbers \end_layout \end_inset \end_layout \begin_layout Verbatim 0 123 104341 \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset String is a sequence of characters enclosed in double quotes \begin_inset Index idx status collapsed \begin_layout Plain Layout Strings \end_layout \end_inset \end_layout \begin_layout Verbatim "file.txt" "This is a string" "dir *.doc" \end_layout \begin_layout Standard The strings in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are used for file names and operating system commands. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Nine special two-character atoms \end_layout \begin_layout Verbatim ** _| / \backslash |= ~~ .. <= >= -> \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Any other characters are considered as single-character atoms. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{list} \end_layout \end_inset \end_layout \begin_layout Standard The format of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset commands is free. They can span one or several lines and any number of spaces and tabulations can be inserted between two neighbor atoms. \end_layout \begin_layout Standard \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{3mm} \end_layout \end_inset \end_layout \begin_layout Standard The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset session may consist of several independent tasks. The command \begin_inset Index idx status collapsed \begin_layout Plain Layout Tasks \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Quit \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Quit; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset terminates both \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset session and returns the control to the operating system level. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Stop \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Stop; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset terminates current \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task and brings the session control menu: \begin_inset Index idx status collapsed \begin_layout Plain Layout Session control menu \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Stop; \end_layout \begin_layout Standard Quit GRG - 0 Start Task - 1 Exit to REDUCE - 2 \end_layout \begin_layout Standard Type 0, 1 or 2: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \begin_inset Newpage newpage \end_inset \end_layout \begin_layout Standard \noindent The option \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset 0 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset terminates \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset session similarly to the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Quit; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The choice \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset 1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset starts new task by bringing \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset to its initial state: all variables, declarations, substitutions and results of calculations are cleared and all switches resume their initial positions. \begin_inset Foot status collapsed \begin_layout Standard Usually \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset does good job by resuming initial state and new task turns out to be independent of previous ones. But on some rare occasions the initial state cannot be completely recovered and it is better to restart \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset completely. \end_layout \end_inset Finally the option \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset 2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset terminates \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task and returns control to the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset command level. In this case \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset can be restarted later by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset grg; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard The commands in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are case insensitive, i.e. command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Quit; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is equivalent to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset quit; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset QUIT; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset etc. But notice that unlike \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset variables and functions in mathematical expressions in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset \emph on are case sensitive \emph default . \end_layout \begin_layout Subsection Switches \end_layout \begin_layout Standard \begin_inset Index idx status collapsed \begin_layout Plain Layout Switches \end_layout \end_inset \end_layout \begin_layout Standard Switches in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset are used to control various system modes of operation. They are denoted by identifiers and the commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset On \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Off \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset On \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset \family typewriter Off \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset turns the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset on and off respectively. Any switch defined by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset is available in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset as well. In addition \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset defines a couple of its own switches. The full list of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset switches is presented in appendix A. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show Switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or equivalently \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset ? \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints current \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset position \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Show Switch TORSION; TORSION is Off. <- On torsion,gcd; <- switch torsion; TORSION is On. <- switch exp; GCD is On \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Switches in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are case insensitive. \end_layout \begin_layout Subsection \family typewriter Batch File Execution \end_layout \begin_layout Standard \family typewriter Usually \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset works in the interactive mode which is not always convenient. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Input \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Batch file execution \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Input \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset reads the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and executes commands stored in it. The file names in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are always denoted by strings and exact specification of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is operating system dependent. The word \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Input \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is optional, thus in order to run batch file it suffices to enter its name \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The execution of batch file commands can be suspended by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Pause \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Pause; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset After this command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset enters the interactive mode. One can enter one or several commands interactively and then resume batch file execution by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Next \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Next; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter In general no any special end-of-file symbol or command is required in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset batch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset but is necessary the symbol \begin_inset Index idx status collapsed \begin_layout Plain Layout end-of-file symbol \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset $ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset $ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is recognized by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset as the end-of-file mark. \end_layout \begin_layout Standard \family typewriter If during the batch file execution an error occurs \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset enter interactive mode and ask user to input the command which is supposed to replace the erroneous one. After the receiving of \emph on one \emph default command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset automatically resumes the batch file execution. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Pause; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be used if it is necessary to execute \emph on several \emph default commands instead of one. \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Output \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Output \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset outfile \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset redirects all \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset output into the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset outfile \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset outfile \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be closed by the equivalent commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset EndO \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset End of Output \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset EndO; \begin_inset Newline newline \end_inset End of Output; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter It is convenient to run long-time \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset tasks in background. The way of doing this depend on the operating system. For example to execute \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task in background in UNIX it is necessary to use the following command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter reduce < task.grg > grg.out & \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Here we assume that the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset invoking command is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset reduce \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and the file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset task.grg \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset contains the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task commands: \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter load grg; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset grg command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset grg command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; ... \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset grg command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; quit; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The output of the session will be written into the file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grg.out \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter Since no proper reaction on errors is possible during the background execution it is good idea to turn the switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset BATCH \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset on. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset BATCH \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset This makes \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset to terminate the session immediately in the case of any error. \end_layout \begin_layout Subsection \family typewriter Operating System Commands \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset System \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset System \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset executes the operating system \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The same command without parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset System; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset temporary suspends \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset session and passes the control to the operating system command level. The details may depend on the concrete operating system. In particular in UNIX the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset system; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset may fail but UNIX has some general mechanism for suspending running programs: you can press \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Ẑ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to suspend any program and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset %+ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to resume its execution. \end_layout \begin_layout Subsection \family typewriter Comments \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout % \backslash reversemarginpar \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The comment commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Comment \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Comment \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset any text \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset % \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset any text \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are used to supply additional information to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset tasks \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "Unload" plural "false" caps "false" noprefix "false" \end_inset about the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and data saved by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. The comment can be also attached to the end of any \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset grg command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset % \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset any text \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout % \backslash normalmarginpar \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Timing \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Time \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show Time \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Time; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints time elapsed since the beginning of current \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task including the percentage of so called garbage collections. The garbage collection time can be also printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset GC Time \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show GC Time \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset GC Time; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter If percentage of garbage collections grows and exceeds say 30% then memory of your system is running short and you probably need more RAM. \end_layout \begin_layout Section \family typewriter Declarations \end_layout \begin_layout Standard \family typewriter Any object, variable or function in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset must be declared. This allows to locate misprints and makes the system more reliable. Since \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset always work in some concrete coordinate system (map) the coordinate declaration is the most important one and must be present in every \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task. \end_layout \begin_layout Subsection \family typewriter Dimension and Signature \end_layout \begin_layout Standard \family typewriter During installation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset always defines default value of the dimension and signature. \begin_inset Index idx status collapsed \begin_layout Plain Layout Dimension!default \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Signature!default \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset tuning \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to find out how to change the default dimension and signature. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The information about this default value is printed \begin_inset Index idx status collapsed \begin_layout Plain Layout Dimension \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Signature \end_layout \end_inset upon \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset start in the form of the following (or similar) message line: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset Dimension is 4 with Signature (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The following command overrides the default dimension and signature \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Dimension \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Dimension \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset dim \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Signature \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset pm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ); \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset dim \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the number \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset 2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or greater and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset pm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset + \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset - \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset pm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be preceded or succeeded by a number which denotes several repetitions of this \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset pm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . For example the declarations \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Dimension 5 with Signature (+,+,-,-,-); Dimension 5 with (2+,-3); \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter are equivalent and defines 5-dimensional space with the signature \begin_inset Formula ${\rm diag}{\scriptstyle(+1,+1,-1,}$ \end_inset \begin_inset Formula ${\scriptstyle-1,-1)}$ \end_inset . \end_layout \begin_layout Standard \family typewriter The important point is that the dimension declaration must be \emph on very first in the task \emph default and goes before any other command. Current dimension and signature can be printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Status; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Coordinates \end_layout \begin_layout Standard \family typewriter The coordinate declaration command must be present in every \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Only few commands such as informational commands, other declarations, switch changing commands may precede the coordinate declaration. The only way to have a tusk without the coordinate declaration is to load the file where coordinates where saved by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset UnloadLoad \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to find out how to save data and declarations into a file. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset but no any computation can be done before coordinates are declared. Current coordinate list can be printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdindx{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout }{ \end_layout \end_inset Coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write Coordinates; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset Float table wide false sideways false status open \begin_layout Standard \align center \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Constants!predefined \end_layout \end_inset \begin_inset Tabular <lyxtabular version="3" rows="11" columns="2"> <features rotate="0" tabularvalignment="middle" tabularwidth="0pt"> <column alignment="left" valignment="top"> <column alignment="left" valignment="top"> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter E I PI INFINITY \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Mathematical constants \begin_inset Formula $e,i,\pi$ \end_inset , \begin_inset Formula $\infty$ \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter FAILED \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter ECONST \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Charge of the electron \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter DMASS \end_layout \end_inset </cell> <cell alignment="left" valignment="top" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Dirac field mass \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter SMASS \end_layout \end_inset </cell> <cell alignment="left" valignment="top" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Scalar field mass \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter GCONST \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Gravitational constant \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter CCONST \end_layout \end_inset </cell> <cell alignment="left" valignment="top" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Cosmological constants \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter LC0 LC1 LC2 LC3 \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Parameters of the quadratic \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter LC4 LC5 LC6 \end_layout \end_inset </cell> <cell alignment="left" valignment="top" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter gravitational Lagrangian \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter MC1 MC2 MC3 \end_layout \end_inset </cell> <cell alignment="none" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter AC0 \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Nonminimal interaction constant \end_layout \end_inset </cell> </row> </lyxtabular> \end_inset \begin_inset Caption Standard \begin_layout Plain Layout Predefined constants \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "predefconstants" \end_inset \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Constants \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Constants \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Any constant must be declared by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Constants \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Constants \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The list of currently declared constants can be printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdindx{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout }{ \end_layout \end_inset Constants \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write Constants; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset There are also a number of built-in constants which are listed in table \begin_inset CommandInset ref LatexCommand ref reference "predefconstants" plural "false" caps "false" noprefix "false" \end_inset . \end_layout \begin_layout Subsection \family typewriter Functions \end_layout \begin_layout Standard \family typewriter Functions in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are the analogues of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset \emph on operators \emph default but we prefer to use this traditional mathematical term. The function must be declared by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Functions \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Functions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the function identifier. The optional list of parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines function with \emph on implicit \emph default dependence. The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset must be either coordinate or constant. The construction \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (*) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is a shortcut which declares the function \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset depending on \emph on all coordinates \emph default . \end_layout \begin_layout Standard \family typewriter The following example declares three functions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun3 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The function \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , which was declared without implicit coordinate list, must be always used in mathematical expressions together with the explicit arguments like \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun1(x+y) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset etc. The functions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun3 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can appear in expressions in similar fashion but also as a single symbol \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset fun3 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- Constant a; <- Functions fun1, fun2(x,y), fun3(*); <- Write functions; Functions: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset fun1 fun2(x,y) fun3(t,x,y,z) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- d fun1(x+a); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset DF(fun1(a + x),x) d x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- d fun2; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset DF(fun2,x) d x + DF(fun2,y) d y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- d fun3; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset DF(fun3,t) d t + DF(fun3,x) d x + DF(fun3,y) d y + DF(fun3,z) d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The functions may have particular properties with respect to their arguments permutation and sign. The corresponding declarations are \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Symmetric \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Antisymmetric \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Odd \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Even \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Symmetric \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset Antisymmetric \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset Odd \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset Even \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Notice that these commands are valid only after function \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset was declared by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Function \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter In addition to user-defined there is also large number of functions predefined in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset . All these functions can be used in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset without declaration. The complete list of these functions depends on \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset versions. Any function defined in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset package (module) is available too if the package is loaded before \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset was started or during \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset session. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset packages \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to find out how to load the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset packages. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset For example the package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset specfn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset contains definitions for various special functions. \end_layout \begin_layout Standard \family typewriter Finally there is also special declaration \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Generic Functions \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Generic Functions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset This command is valid iff the package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset dfpart.red \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is installed on your \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset system. Here unlike the usual function declaration the list of parameters must be always present and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be any identifier preferably distinct from any other variable. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset genfun \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to find out about the generic functions. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The role of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is also completely different and is explained later. \end_layout \begin_layout Standard \family typewriter The list of declared functions can be printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdindx{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout }{ \end_layout \end_inset Functions \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write Functions; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Generic functions in this output are marked by the label \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset * \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Subsection \family typewriter Affine Parameter \end_layout \begin_layout Standard \family typewriter The variable which plays the role of affine parameter in the geodesic equation must be declared by the command \begin_inset CommandInset label LatexCommand label name "affpar" \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Affine Parameter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset s \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and can be printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdindx{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout }{ \end_layout \end_inset Affine Parameter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write Affine Parameter; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset VSpace vfill \end_inset \begin_inset Newpage newpage \end_inset \end_layout \begin_layout Subsection \family typewriter Case Sensitivity \end_layout \begin_layout Standard \family typewriter \begin_inset CommandInset label LatexCommand label name "case" \end_inset \end_layout \begin_layout Standard \family typewriter Usually \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset is case insensitive which means for example that expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset x-X \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset will be evaluated by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset as zero. On the contrary all coordinates, constants and functions in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are case sensitive, e.g. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset alpha \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Alpha \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ALPHA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are all different. Notice that commands and switches in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash \end_layout \begin_layout Plain Layout \end_layout \end_inset 3.2 remain case insensitive. \begin_inset Index idx status collapsed \begin_layout Plain Layout Internal \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset case \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Therefore all predefined by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset constants and all built-in objects must be used exactly as they presented in this manual \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset GCONST \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SMASS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset etc. The situation with the constants and functions which predefined by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset is different. The point is that in spite of its default case insensitivity internally \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset converts everything into some default case which may be upper or lower. Therefore depending on the particular \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset system they must be typed either as \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter E I PI INFINITY SIN COS ATAN \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter or in lower case \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter e i pi infinity sin cos atan \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter For the sake of definiteness throughout this book we chose the first upper case convention. \end_layout \begin_layout Standard \family typewriter When \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset starts it informs you about internal case of your particular \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset system by printing the message \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset System variables are upper-cased: E I PI SIN ... \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset System variables are lower-cased: e i pi sin ... \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset You can find out about the internal case using the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Status; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset VSpace vfill \end_inset \begin_inset Newpage newpage \end_inset \end_layout \begin_layout Subsection \family typewriter Complex Conjugation \end_layout \begin_layout Standard \family typewriter By default all variables and functions in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are considered to be real excluding the imaginary unit constant \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset I \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset i \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset as explained above). But if two identifiers differ only by the trailing character \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset they are considered as a pair of complex variables which are conjugated to each other. In the following example coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset z \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset comprise such a pair: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates u, v, z, z \begin_inset space ~ \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset z & z \begin_inset space ~ \end_inset - conjugated pair. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Re(z); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset z + z \begin_inset space ~ \end_inset ——– 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Im(z \begin_inset space ~ \end_inset ); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset I*(z - z \begin_inset space ~ \end_inset ) ———— 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Section \family typewriter Objects \end_layout \begin_layout Standard \family typewriter Objects play a fundamental role in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset . They represent mathematical quantities such as metric, connection, curvature and any other spinor or tensor geometrical and physical fields and equations. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset has quite large number of built-in objects and knows many formulas for their calculation. But you are not obliged to use the built-in quantities and can declare your own. The purpose of the declaration is to tell \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset basic properties of a new quantity. \end_layout \begin_layout Subsection \family typewriter Built-in Objects \end_layout \begin_layout Standard \noindent \family typewriter An object is characterized by the following properties and attributes: \begin_inset Index idx status collapsed \begin_layout Plain Layout Built-in objects \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{list} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset Formula $\bullet$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash labelwidth \end_layout \end_inset =4mm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash leftmargin \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parindent \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parsep \end_layout \end_inset =0mm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Name \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Identifier or symbol \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Type of the component \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset List of indices \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Symmetries with respect to index permutation \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Density and pseudo-tensor property \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Built-in ways of calculation \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Value \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{list} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The object \emph on name \emph default is a sequence of words which are usually the common English name of corresponding quantity. The name is case insensitive and is used to denote a particular object in commands. So called \emph on group names \emph default \begin_inset Index idx status collapsed \begin_layout Plain Layout Group names \end_layout \end_inset refer to a collection of closely related objects. In particular the name Curvature Spinors \family typewriter \series default \shape default (see page \begin_inset CommandInset ref LatexCommand pageref reference "curspincoll" plural "false" caps "false" noprefix "false" \end_inset ) refers to the irreducible components of the curvature tensor in spinorial representation. Actual content of the group may depend on the environment. In particular the group Curvature Spinors \family typewriter \series default \shape default includes three objects in the Riemann space (Weyl spinor, traceless Ricci spinor and scalar curvature) while in the space with torsion we have six irreducible curvature spinors. \end_layout \begin_layout Standard \family typewriter The object \emph on identifier \emph default or \emph on symbol \emph default is an identifier which denotes the object in mathematical expressions. Object symbols are case sensitive. \end_layout \begin_layout Standard \family typewriter The object \emph on type \emph default is the type of its component: objects can be scalar, vector or \begin_inset Formula $p$ \end_inset -form valued. The \emph on density \emph default and \emph on pseudo-tensor \emph default properties of the object characterizes its behaviour under coordinate and frame transformations. \end_layout \begin_layout Standard \family typewriter Objects can have the following types of indices: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{list} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset Formula $\bullet$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash labelwidth \end_layout \end_inset =4mm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash leftmargin \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parindent \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Upper and lower holonomic coordinate indices. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Upper and lower frame indices. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Upper and lower spinorial indices. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Upper and lower conjugated spinorial indices. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Enumerating indices. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{list} \end_layout \end_inset The major part of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset built-in objects has frame indices. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "metric" plural "false" caps "false" noprefix "false" \end_inset about the frame in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The frame in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset can be arbitrary but you can easily specify the frame to be holonomic or say orthogonal. Then built-in object indices become holonomic or orthogonal respectively. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset deals only with the SL(2,C) spinors which are restricted to the 4-dimensional spaces of Lorentzian signature. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset spinors \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset about the spinorial formalism in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The corresponding SL(2,C) indices take values 0 and 1. The conjugated indices are transformed with the help of the complex conjugated SL(2,C) matrix. If some spinor is totally symmetric in the group of \begin_inset Formula $n$ \end_inset spinorial indices (irreducible spinor) then these indices can be replaced by a single so called \emph on summed spinorial index \emph default of rank \begin_inset Formula $n$ \end_inset which take values from 0 to \begin_inset Formula $n$ \end_inset . The summed spinorial indices provide the most economic way to store the irreducible spinor components. \end_layout \begin_layout Standard \family typewriter Enumerating indices just label a collection of values and have no any covariant meaning. Accordingly there is no difference between upper and lower enumerating indices. \end_layout \begin_layout Standard \family typewriter Notice that an index of any type in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset always runs from 0 up to some maximal value which depend on the index type and dimensionality: \begin_inset Formula $d-1$ \end_inset for frame and coordinate indices, \begin_inset Index idx status collapsed \begin_layout Plain Layout Dimension \end_layout \end_inset and \begin_inset Formula $n$ \end_inset the spinor indices of the rank \begin_inset Formula $n$ \end_inset . \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset understands various types of index symmetries: symmetry, antisymmetry, cyclic symmetry and Hermitian symmetry. These symmetries can apply not only to single indices but to any group of indices as well. \begin_inset Index idx status collapsed \begin_layout Plain Layout Index symmetries \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Canonical order of indices \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset uses object symmetries to decrease the amount of memory required to store the object components. It stores only components with the indices in certain \emph on canonical \emph default order and any other component are automatically restored if necessary by appropriate index permutation. The canonical order of indices is defined as follows: for symmetry, antisymmetry or Hermitian symmetry indices are sorted in such a way that index values grows from left to the right. For cyclic symmetry indices are shifted to minimize the numerical value of the whole list of indices. \end_layout \begin_layout Standard \family typewriter Finally there are two special types of objects: equations and connection 1-forms. \begin_inset Index idx status collapsed \begin_layout Plain Layout Equations \end_layout \end_inset Equations have all the same properties as any other object but in addition they have left and right hand side and are printed in the form of equalities. The connections are used by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset to construct covariant derivatives. \begin_inset Index idx status collapsed \begin_layout Plain Layout Connections \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset conn2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset about the connections. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset There are only four types of connections: holonomic connection 1-form, frame connection 1-form, spinor connection 1-form and conjugated spinor connection 1-form. \end_layout \begin_layout Standard \family typewriter Almost all built-in objects have associated built-in \emph on ways of calculation \emph default (one or several). \begin_inset Index idx status collapsed \begin_layout Plain Layout Ways of calculation \end_layout \end_inset Each way is nothing but a formula which can be used to obtain the object value. \end_layout \begin_layout Standard \family typewriter Every object can be in two states. Initially when \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset starts all objects are in \emph on indefinite \emph default state, i.e. nothing is known about their value. \begin_inset Index idx status collapsed \begin_layout Plain Layout Object value \end_layout \end_inset Since \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset always works in some concrete frame and coordinate system the object value is a table of the components. As soon as the value of certain object is obtained either by direct assignment or using some built-in formula (way of calculation) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset remember this value and store it in some internal table. Later this value can be printed, re-evaluated used in expression etc. The object can be returned to its initial indefinite state using the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset uses object symmetries to reduce total number of components to store. \end_layout \begin_layout Standard \family typewriter The complete list of built-in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset objects is given in appendix C. The chapter 3 also describes built-in objects but in the usual mathematical style. The equivalent commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset ? \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints detailed information about the object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset including object name, identifier, list of indices, type of the component, current state (is the value of an object known or not), symmetries and ways of calculation. Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is either object name or its identifier. \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show * \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Show *; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints complete list of built-in object names. This list is quite long and the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset c \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset *; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset gives list of objects whose names begin with the character \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset c \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset – \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset z \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ). \end_layout \begin_layout Standard \family typewriter Finally the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show All \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Show All; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints list of objects whose values are currently known. \end_layout \begin_layout Standard \family typewriter Notice that some built-in objects has limited scope. In particular some objects exists only in certain dimensionality, the quantities which are specific to spaces with torsion are defined iff switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset TORSION \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is turned on etc. \end_layout \begin_layout Standard \family typewriter Let us consider some examples. We begin with the curvature tensor \begin_inset Formula $R^a{}_{bcd}$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Show Riemann Tensor; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Riemann tensor RIM'a.b.c.d is Scalar Value: unknown Symmetries: a(3,4) Ways of calculation: Standard way (D,OMEGA) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset This object has name Riemann Tensor \family typewriter \series default \shape default and identifier RIM \family typewriter \series default \shape default . The object is Scalar \family typewriter \series default \shape default (0-form) valued and has four frame indices. Frame indices are denoted by the lower-case characters and their upper or lower position are denoted by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ' \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset respectively. The Riemann tensor is antisymmetric in two last indices which is denoted by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a(3,4) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter The curvature 2-form \begin_inset Formula $\Omega^a{}_b$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- ? OMEGA; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Curvature OMEGA'e.f is 2-form Value: unknown Ways of calculation: Standard way (omega) From spinorial curvature (OMEGAU*,OMEGAD) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset has name Curvature \family typewriter \series default \shape default and the identifier OMEGA \family typewriter \series default \shape default and is 2-form valued. \end_layout \begin_layout Standard \family typewriter The traceless Ricci spinor (the quantity which is usually denoted in the Newman-Penrose formalism as \begin_inset Formula $\Phi_{AB\dot{C}\dot{D}}$ \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- ? Traceless Ricci Spinor; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Traceless ricci spinor RC.AB.CD \begin_inset space ~ \end_inset is Scalar Value: unknown Symmetries: h(1,2) Ways of calculation: From spinor curvature (OMEGAU,SD,VOL) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Spinorial indices are denoted by upper case characters with the trailing \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset for conjugated indices. Usual spinorial indices are denoted by a \emph on single \emph default upper case letter while summed indices are denoted by several characters. Thus, the traceless Ricci spinor has two summed spinorial indices of rank 2 each taking the values from 0 to 2. The spinor is hermitian \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset h(1,2) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter The Einstein equation is an example of equation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- ? Einstein Equation; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Einstein equation EEq.g.h is Scalar Equation Value: unknown Symmetries: s(1,2) Ways of calculation: Standard way (G,RIC,RR,TENMOM) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset and 1-form \begin_inset Formula $\Gamma^\alpha{}_\beta$ \end_inset is an example of the connection \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{2mm} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Show Holonomic Connection; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reversemarginpar \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Holonomic connection GAMMAxy is 1-form Holonomic Connection Value: unknown Ways of calculation: From frame connection (T,D,omega) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset The coordinate indices are denoted by the lower-case letters with labels \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ˖̂ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset _ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset denoting upper and lower index position respectively. Notice that above the first \begin_inset Quotes eld \end_inset Holonomic connection \family typewriter \series default \shape default \begin_inset Quotes erd \end_inset is the name of the object while second \begin_inset Quotes eld \end_inset Holonomic Connection \family typewriter \series default \shape default \begin_inset Quotes erd \end_inset means that \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset recognizes it as the connection and will use \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset GAMMA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to construct covariant derivatives for quantities having the coordinate indices. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset cder \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset about the covariant derivatives. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset You can define any number of other holonomic connections and use them in the covariant derivatives on the equal footing with the built-in object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset GAMMA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash normalmarginpar \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The notation in which command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints information about a particular object is the same as in the new object declaration and is explained in details below. \end_layout \begin_layout Subsection \family typewriter Macro Objects \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Macro Objects \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "macro" \end_inset \end_layout \begin_layout Standard \family typewriter There is also another class of built-in objects which are called \emph on macro objects \emph default . The main difference between the usual and macro objects is that macro quantities has no permanent storage to their components instead they are calculated dynamically only when its component is required in some expression. In addition they do not have names and are denoted only by the identifier only. Usually macro objects play auxiliary role. The complete list of macro objects can be found in appendix B. \end_layout \begin_layout Standard \family typewriter The example of macro objects are the Christoffel symbols of second and first kind \begin_inset Formula $\{{}^\alpha_{\beta\gamma}\}$ \end_inset and \begin_inset Formula $[{}_{\alpha,\beta\gamma}]$ \end_inset having identifiers \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset CHR \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset CHRF \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset respectively \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Show CHR; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset CHRxyz is Scalar Macro Object Symmetries: s(2,3) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- ? CHRF; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset CHRFuvw is Scalar Macro Object Symmetries: s(2,3) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter New Object Declaration \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset has very large number of built-in quantities but you are not obliged to use them in your calculations instead you can define new quantities. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset New Object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset New Object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ilst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ctype \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Symmetries \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset declares a new object. The words \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset New \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are optional (but not both) so the above command are equivalent to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ilst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ctype \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Symmetries \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset New \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ilst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ctype \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Symmetries \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is an identifier of a new object. The identifier can contain letters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset – \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset z \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset – \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Z \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset but neither digits nor any other symbols. The identifier must be unique and cannot coincide with the identifier of any other built-in or user-defined object. \end_layout \begin_layout Standard \family typewriter The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ilist \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the list of indices having the form \begin_inset CommandInset label LatexCommand label name "indices" \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ipos \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \space{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset itype \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ipos \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines the index position and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset itype \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset specifies its type. The coordinate holonomic and frame indices are denoted by single lower-case letters with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ipos \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset ' \family typewriter \series default \shape default \family roman \begin_inset space \space{} \end_inset \begin_inset space \space{} \end_inset upper frame index \begin_inset Newline newline \end_inset \family typewriter . \family roman \series default \shape default \begin_inset space \space{} \end_inset \begin_inset space \space{} \end_inset lower frame index \begin_inset Newline newline \end_inset \family typewriter ˖̂ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \family roman \begin_inset space \space{} \end_inset \begin_inset space \space{} \end_inset upper holonomic index \begin_inset Newline newline \end_inset \family typewriter _ \family roman \series default \shape default \begin_inset space \space{} \end_inset \begin_inset space \space{} \end_inset lower holonomic index \family roman \series default \shape default The frame and holonomic indices in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset take values from 0 to \begin_inset Formula $d-1$ \end_inset where \begin_inset Formula $d$ \end_inset is the current space dimensionality. \begin_inset Index idx status collapsed \begin_layout Plain Layout Dimension \end_layout \end_inset \end_layout \begin_layout Standard \family roman Spinorial indices are denoted by upper case letters with trailing \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset for conjugated spinorial indices: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset etc. Summed spinorial index of rank \begin_inset Formula $n$ \end_inset is denoted by \begin_inset Formula $n$ \end_inset upper-case letters. For example \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ABC \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset denotes summed spinorial index of the rank 3 (runs from 0 to 3) and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset denotes conjugated summed index of the rank 2 (values 0, 1, 2). The upper position for spinorial indices are denoted either by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ' \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ˖̂ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and lower one by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset _ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family roman Finally the enumerating indices are denoted by a single lower-case letter followed either by digits or by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset dim \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . For example the index declared as \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset i2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset runs from 0 to 2 while specification \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a13 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset denotes index whose values runs from 0 to 13. The specification \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset idim \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset denotes enumerating index which takes the values from 0 to \begin_inset Formula $d-1$ \end_inset . Upper of lower position for enumerating indices are identical, thus in this case symbols \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ' . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ^{ \backslash _} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are equivalent. \end_layout \begin_layout Standard \family roman The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ctype \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines the type of new object component: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Scalar \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Density \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset dens \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Newline newline \end_inset \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset p \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset -form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Density \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset dens \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Newline newline \end_inset Vector \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Density \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset dens \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset This part of the declaration can be omitted and then the object is assumed to be scalar-valued. The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset dens \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines pseudo-scalar and density properties of the object with respect to coordinate and frame transformations: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset sgnL \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset *sgnD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset *L \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ^{ \backslash parm} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset *D \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ^{ \backslash parm} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset m \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset D \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the coordinate transformation determinant \begin_inset Formula ${\rm det}(\partial x^{\alpha'}/\partial x^\beta)$ \end_inset and frame transformation determinant \begin_inset Formula ${\rm det}(L^a{}_b)$ \end_inset respectively. If \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset sgnL \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset sgnD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is specified then under appropriate transformation the object must be multiplied on the sign of the corresponding determinant (pseudo tensor). The specification \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ^{ \backslash parm} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset D \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ^{ \backslash parm} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset m \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset means that the quantity must be multiplied on the appropriate degree of the corresponding determinant (tensor density). The parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset p \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset m \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset may be given by expressions (must be enclosed in brackets) but value of these expressions must be always integer and positive in the case of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset p \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter The symmetry specification \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is a list \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where each element \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset describes symmetries for one group of indices and has the form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sym \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sym \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset determines type of the symmetry \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset s \begin_inset space \space{} \end_inset \family roman symmetry \begin_inset Newline newline \end_inset \family typewriter a \begin_inset space \space{} \end_inset \family roman antisymmetry \begin_inset Newline newline \end_inset \family typewriter c \begin_inset space \space{} \end_inset \family roman cyclic symmetry \begin_inset Newline newline \end_inset \family typewriter h \begin_inset space \space{} \end_inset \family roman Hermitian symmetry \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is either index number \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset i \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or list of index numbers \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset i \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or another symmetry specification of the form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Notice that \begin_inset Formula $n$ \end_inset th object index can be present only in one of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family roman Let us consider an object having four indices. Then the following symmetry specifications are possible \end_layout \begin_layout Standard \family roman \begin_inset Tabular <lyxtabular version="3" rows="6" columns="2"> <features rotate="0" tabularvalignment="middle" tabularwidth="0pt"> <column alignment="left" valignment="top"> <column alignment="left" valignment="top"> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset s(1,2,3,4) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman total symmetry \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman [1mm] \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a(1,2),s(3,4) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman antisymmetry in first pair of indices and \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman symmetry in second pair \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman [1mm] \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset s((1,2),(3,4)) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman symmetry in pair permutation \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman [1mm] \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset s(a(1,2),a(3,4)) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman antisymmetry in first and second pair of indices \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family roman and symmetry in pair permutation \end_layout \end_inset </cell> </row> </lyxtabular> \end_inset \begin_inset Newline newline \end_inset The last example is the well known symmetry of Riemann curvature tensor. The specification \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a(1,2),s(2,3) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is erroneous since second index present in both parts of the specification which is not allowed. \end_layout \begin_layout Standard \family roman Declaration for new equations is completely similar \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset New Equation \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset New \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Equation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ilst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ctype \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Symmetries \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset slst \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family roman \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset knows four types of connections: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset New Connection \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "conn2" \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{list} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset Formula $\bullet$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash labelwidth \end_layout \end_inset =4mm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash leftmargin \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parindent \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family roman \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Frame Connection 1-form \begin_inset Formula $\omega^a{}_b$ \end_inset having first upper and second lower frame indices \end_layout \begin_layout Standard \family roman \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Holonomic Connection 1-form \begin_inset Formula $\Gamma^\alpha{}_\beta$ \end_inset having first upper and second lower coordinate indices \end_layout \begin_layout Standard \family roman \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Spinor Connection 1-form \begin_inset Formula $\omega_{AB}$ \end_inset with lower spinor index of rank 2 \end_layout \begin_layout Standard \family roman \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Conjugated Spinor Connection \begin_inset Formula $\omega_{\dot{A}\dot{B}}$ \end_inset 1-form with lower conjugated spinor index of rank 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{list} \end_layout \end_inset Each of these connections are used to construct covariant derivatives with respect to corresponding indices. In addition they are properly transformed under the coordinate change and frame rotation. There are complete set of built-in connections but you can declare a new one by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset New \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Connection \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset 'a.b \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is 1-form \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset New \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Connection \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset m̂_n \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is 1-form \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset New \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Connection \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset .AB \begin_inset space \space{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is 1-form \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset New \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Connection \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset .AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset space \space{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset is 1-form \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Notice that any new connection must belong to one of the listed above types and have indicated type and position of indices. This representation of connection is chosen in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset for the sake of definiteness. \end_layout \begin_layout Standard \family typewriter There is one special case when new object can be declared without explicit \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset New Object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset declaration. Let us consider the following example: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- www=d x; <- Show www; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset www is 1-form Value: known \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset If we assign the value to some identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset www \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset in our example) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "assig" plural "false" caps "false" noprefix "false" \end_inset about assignment command. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and this identifier is not reserved yet by any other object then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset automatically declares a new object without indices labeled by the identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and having the type of the expression in the right-hand side of the assignment (1-form in our example). Notice that the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset must not include digits since digits represent indices and any new object with indices must be declared explicitly. \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Forget \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset completely removes the user-defined object with the identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter Finally let us consider some examples: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- New RNEW'a.bcd is scalar density sgnD with a(3,4); <- Show RNEW; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset RNEW'a.bxy is Scalar Density sgnD Value: unknown Symmetries: a(3,4) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Null Metric; <- Connection omnew.AA; <- Show omnew; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset omnew.AB is 1-form Spinor Connection Value: unknown \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Here the first declaration defines a new scalar valued pseudo tensor \begin_inset Formula $\mbox{\comm{RNEW}}^a{}_{b\gamma\delta}$ \end_inset which is antisymmetric in the last pair of indices. Second declaration introduce new spinor connection \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset omnew \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Notice that new connection is automatically declared 1-form and the type of connection is derived by the type of new object indices (lower spinorial index of rank 2 in our example). \end_layout \begin_layout Section \family typewriter Assignment Command \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Assignment (command) \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "assig" \end_inset \end_layout \begin_layout Standard \family typewriter The assignment command sets the value to the particular components of the object. In general it has the form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset Name \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset comp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or for equations \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset Name \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset comp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset lhs \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset rhs \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset Name \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the optional object name. If the object has no indices then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset comp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the object identifier. If the object has indices then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset comm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset consist of identifier with additional digits denoting indices. For example the following command assigns standard spherical flat value to the frame \begin_inset Formula $\theta^a$ \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Frame T0 = d t, T1 = d r, T2 = r*d theta, T3 = r*SIN(theta)*d phi; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter and the command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter RIM0123 = 100; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter assigns the value to the \begin_inset Formula $R^0{}_{123}$ \end_inset component of the Riemann tensor. Notice that in this notation each digit is considered as one index, thus it does not work if the value of some index is greater than 9 (e.g. if dimensionality is 10 or greater). In this case another notation can be used in which indices are added to the object identifier as a list of digits enclosed in brackets \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset Name \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset space ~ \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset In particular the command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter RIM(0,1,2,3) = 100; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter is equivalent to the example above. \end_layout \begin_layout Standard \family typewriter The assignment set value only to the certain components of an object leaving other components unchanged. But if before assignment the object was in indefinite state (no value is known) then assignment turns it to the definite state and all other components of the object are assumed to be zero. \end_layout \begin_layout Standard \family typewriter The digits standing for object indices in the left-hand side of an assignment can be replaced by identifiers \begin_inset Index idx status collapsed \begin_layout Plain Layout Assignment (command)!tensorial \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset Name \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset ID \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset space ~ \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Such assignment is called \emph on tensorial \emph default one. For example the following tensorial assignment set the value to the curvature 2-form \begin_inset Formula $\Omega^a{}_b$ \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter OMEGA(a,b) = d omega(a,b) + omega(a,m) \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset omega(m,b); \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter This command is equivalent to \begin_inset Formula $d\times d$ \end_inset of assignments where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset b \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset take values from 0 to \begin_inset Formula $d-1$ \end_inset ( \begin_inset Formula $d$ \end_inset is the space dimensionality). \begin_inset Index idx status collapsed \begin_layout Plain Layout Dimension \end_layout \end_inset Notice that identifiers in the left-hand side of tensorial assignment must not coincide with any predefined or declared by the user constant or coordinate. It is possible to mix digits and identifiers: \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter FT(0,a) = 0; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset FT \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is identifier of the built-in object EM Tensor \family typewriter \series default \shape default which is the electromagnetic strength tensor \begin_inset Formula $F_{ab}$ \end_inset and this command sets the electric part of the tensor to zero. \end_layout \begin_layout Standard \family typewriter The assignment command takes into account symmetries of the objects. For example EM Tensor \family typewriter \series default \shape default is antisymmetric and in order to assign value say to the components \begin_inset Formula $F_{01}=-F_{10}$ \end_inset it suffices to do this just for one of them \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- EM Tensor FT01=111, FT(3,2)=222; <- Write FT; EM tensor: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = 111 t x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = -222 y z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset We can see that \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset automatically transforms indices to the \emph on canonical \emph default order. This rule works in the case or tensorial assignment as well \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- Function ff; <- EM Tensor FT(a,b)=ff(a,b); <- Write FT; EM tensor: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ff(0,1) t x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ff(0,2) t y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ff(0,3) t z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ff(1,2) x y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ff(1,3) x z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ff(2,3) y z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- FT(2,1); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset - ff(1,2) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset In this case both parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset b \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset runs from 0 to 3 but \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset assigns the value only to the components having indices in the canonical order \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $<$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset b \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset follows this rule also if in the left-hand side of tensorial assignment digits are mixed with parameters which may sometimes produce unexpected result: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- Function ee; <- FT(0,a)=ee(a); <- Write FT; EM tensor: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ee(1) t x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ee(2) t y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FT = ee(3) t z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Erase FT; <- FT(3,a)=ee(a); <- Write FT; EM tensor: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 0 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Observe the difference between these two assignments (the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Erase FT; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset destroys the previously assigned value). In fact second assignment assigns no values since \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset 3 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are not in the canonical order \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset 3 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $\geq$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset running from 0 to 3. Notice the difference from the case when all indices in the left-hand side are given by the explicit numerical values. In this case \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset automatically transforms the indices to their canonical order and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset FT(3,2)=222; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is equivalent to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset FT(2,3)=-222; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter Finally there is one more form of the tensorial assignment which can be applied to the summed spinorial indices. \begin_inset Index idx status collapsed \begin_layout Plain Layout Assignment (command)!summed spinor indices \end_layout \end_inset Let us consider the spinorial analogue of electromagnetic strength tensor \begin_inset Formula $\Phi_{AB}$ \end_inset . This spinor is irreducible (i.e. symmetric in \begin_inset Formula $\scriptstyle AB$ \end_inset ). The corresponding \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset built-in object Undotted EM Spinor \family typewriter \series default \shape default (identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset FIU \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) has one summed spinorial index of rank 2. Let us consider two different assignment commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates u, v, z, z \begin_inset space ~ \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset z & z \begin_inset space ~ \end_inset - conjugated pair. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Null Metric; <- Function ee; <- FIU(a)=ee(a); <- Write FIU; Undotted EM spinor: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FIU = ee(0) 0 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FIU = ee(1) 1 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FIU = ee(2) 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Erase FIU; <- FIU(a+b)=ee(a,b); <- Write FIU; Undotted EM spinor: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FIU = ee(0,0) 0 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FIU = ee(0,1) 1 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset FIU = ee(1,1) 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset In the first case \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is treated as a summed index and runs from 0 to 2 but in the second case \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset b \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are considered as usual single SL(2,C) spinorial indices each having values 0 and 1. \end_layout \begin_layout Standard \family typewriter The notation for the object components in the left-hand side of assignment do not distinguishes upper and lower indices. Actually the indices are always assumed to be in the default position. You can always check the default index types and positions using the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset For example the Riemann Tensor \family typewriter \series default \shape default has first upper and three lower frame indices and the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset RIM0123=100; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset RIM(0,1,2,3)=100; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset both assign value to the \begin_inset Formula $R^0{}_{123}$ \end_inset component of the tensor where indices are represented with respect to the current frame. \end_layout \begin_layout Section \family typewriter Geometry \end_layout \begin_layout Standard \family typewriter The number of built-in objects in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is rather large. They all described in chapter 3 and appendices B and C. In this section we consider only the most important ones. \end_layout \begin_layout Subsection \family typewriter Metric, Frame and Line-Element \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Metric \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Frame \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "metric" \end_inset \end_layout \begin_layout Standard \family typewriter The line-element in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is defined by the following equation \begin_inset Formula \begin{equation} ds^2 = g_{ab}\,\theta^a\!\otimes\theta^b \end{equation} \end_inset where \begin_inset Formula $\theta^a=h^a_\mu dx^\mu$ \end_inset is the frame 1-form and \begin_inset Formula $g_{ab}$ \end_inset is the frame metric. The corresponding built-in objects are \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Frame \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset T \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Metric \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset G \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ). There are also the \begin_inset Quotes eld \end_inset inverse \begin_inset Quotes erd \end_inset counterparts \begin_inset Formula $\partial_a=h_a^\mu\partial_\mu$ \end_inset (Vector Frame \family typewriter \series default \shape default , identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset D \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) and \begin_inset Formula $g^{ab}$ \end_inset (Inverse Metric \family typewriter \series default \shape default , identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset GI \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ). To determine the metric properties of the space you can assign some values to both the metric and the frame. There are two well known special cases. First is the usual coordinate formalism in which frame is holonomic \begin_inset Formula $\theta^a=dx^\alpha$ \end_inset . In this case there is no difference between frame and coordinate indices. Another representation is known as the tetrad (in dimension 4) formalism. In this case frame metric equals to some constant matrix \begin_inset Formula $g_{ab}=\eta_{ab}$ \end_inset and significant information about line-element \begin_inset Quotes eld \end_inset is encoded \begin_inset Quotes erd \end_inset in the frame. \end_layout \begin_layout Standard \family typewriter In general both metric and frame can be nontrivial but not necessarily. If no any value is given by user to the frame when \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset automatically assumes that frame is \emph on holonomic \emph default \begin_inset Index idx status collapsed \begin_layout Plain Layout Frame!default value \end_layout \end_inset \begin_inset Formula \begin{equation} \theta^a=dx^\alpha \end{equation} \end_inset Thus if we assign the value to metric only we automatically get standard coordinate formalism. On the contrary if no value is assigned to the metric then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset automatically assumes \begin_inset Index idx status collapsed \begin_layout Plain Layout Signature \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "defaultmetric" \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Metric!default value \end_layout \end_inset \begin_inset Formula \begin{equation} g_{ab} = {\rm diag}(+1,-1,\dots) \end{equation} \end_inset where \begin_inset Formula $+1$ \end_inset and \begin_inset Formula $-1$ \end_inset on the diagonal of the matrix correspond to the current signature specification. \end_layout \begin_layout Standard \family typewriter Notice that current signature is printed among other information by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Status; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and current line-element is printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset ds2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset ds2; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or equivalently \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Line-Element \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Line-Element; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Finally if neither frame nor metric are specified by user then both these quantities acquire default value and we automatically obtain flat space of the default signature: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Dimension 4 with Signature(-,+,+,+); <- Coordinates t, x, y, z; <- ds2; Assuming Default Metric. Metric calculated By default. 0.05 sec Assuming Default Holonomic Frame. Frame calculated By default. 0.05 sec \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 2 2 2 ds = - d t + d x + d y + d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Spinors \end_layout \begin_layout Standard \family typewriter \begin_inset CommandInset label LatexCommand label name "spinors" \end_inset \end_layout \begin_layout Standard \family typewriter Spinorial representations exist in spaces of various dimensions and signatures but in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset spinors are restricted to the 4-dimensional spaces of Lorentzian signature \begin_inset Formula ${\scriptstyle(-,+,+,+)}$ \end_inset or \begin_inset Formula ${\scriptstyle(+,-,-,-)}$ \end_inset only. Another restriction is that in the spinorial formalism the metric must be the \begin_inset Index idx status collapsed \begin_layout Plain Layout Metric!Standard Null \end_layout \end_inset \emph on standard null metric \emph default : \begin_inset Index idx status collapsed \begin_layout Plain Layout Standard null metric \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Spinors \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Spinors!Standard null metric \end_layout \end_inset \begin_inset Formula \begin{equation} g_{ab}=g^{ab}=\pm\left(\begin{array}{rrrr} 0 & -1 & 0 & 0 \\ -1 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1 \\ 0 & 0 & 1 & 0 \end{array}\right) \end{equation} \end_inset where upper sign correspond to the signature \begin_inset Formula ${\scriptstyle(-,+,+,+)}$ \end_inset and lower sign to the signature \begin_inset Formula ${\scriptstyle(+,-,-,-)}$ \end_inset . There is special command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Null Metric \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Null Metric; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset which assigns this standard value to the metric. \end_layout \begin_layout Standard \family typewriter Thus spinorial frame (tetrad) in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset must be null \begin_inset Formula \begin{equation} ds^2 = \pm(-\theta^0\!\otimes\theta^1 -\theta^1\!\otimes\theta^0 +\theta^2\!\otimes\theta^3 +\theta^3\!\otimes\theta^2) \end{equation} \end_inset and conjugation rules for this tetrad must be \begin_inset Formula \begin{equation} \overline{\theta^0}=\theta^0,\quad \overline{\theta^1}=\theta^1,\quad \overline{\theta^2}=\theta^3,\quad \overline{\theta^3}=\theta^2 \end{equation} \end_inset \end_layout \begin_layout Standard \family typewriter For the sake of efficiency the sigma-matrices \begin_inset Formula $\sigma^a\!{}_{A\dot{B}}$ \end_inset for such a tetrad are chosen in the simplest form. The only nonzero components of the matrices are \begin_inset Index idx status collapsed \begin_layout Plain Layout Sigma matrices \end_layout \end_inset \begin_inset Formula \begin{eqnarray} &&\sigma_0{}^{1\dot{1}}= \sigma_1{}^{0\dot{0}}= \sigma_2{}^{1\dot{0}}= \sigma_3{}^{0\dot{1}}=1 \\[1mm] && \sigma^0{}_{1\dot{1}}= \sigma^1{}_{0\dot{0}}= \sigma^2{}_{1\dot{0}}= \sigma^3{}_{0\dot{1}}=\mp1 \end{eqnarray} \end_inset \end_layout \begin_layout Subsection \family typewriter Connection, Torsion and Nonmetricity \end_layout \begin_layout Standard \family typewriter \begin_inset CommandInset label LatexCommand label name "conn" \end_inset \end_layout \begin_layout Standard \family typewriter As was explained above \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset recognizes four types of connections: holonomic \begin_inset Formula $\Gamma^\alpha{}_\beta$ \end_inset , frame \begin_inset Formula $\omega^a{}_b$ \end_inset , spinorial \begin_inset Formula $\omega_{AB}$ \end_inset and conjugated spinorial \begin_inset Formula $\omega_{\dot{A}\dot{B}}$ \end_inset . Accordingly there are four built-in objects: Holonomic Connection \family typewriter \series default \shape default (id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset GAMMA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ), Frame Connection \family typewriter \series default \shape default (id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset omega \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ), Undotted Connection \family typewriter \series default \shape default (id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset omegau \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ), Dotted Connection \family typewriter \series default \shape default (id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset omegad \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ). Connections are used in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset in covariant derivatives. In addition they are properly transformed under frame and coordinate transformations. \end_layout \begin_layout Standard \family typewriter By default the connection in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are assumed to be Riemannian. In particular in this case holonomic connection is nothing but Christoffel symbols \begin_inset Formula $\Gamma^\alpha{}_\beta= \{{}^\alpha_{\beta\pi}\}dx^\pi$ \end_inset . If it is necessary to work with torsion and/or nonmetricity \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset TORSION \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset NONMETR \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset then the switches \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset TORSION \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and/or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset NONMETR \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset must be turned on. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset conn2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset about the built-in connections. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset In this case the Riemannian analogues or the aforementioned four connections are available as well. \end_layout \begin_layout Section \family typewriter Expressions \end_layout \begin_layout Standard \family typewriter Expressions in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset can be algebraic (scalar), vector or p-form valued. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset knows all the usual mathematical operations on algebraic expressions, exterior forms and vectors. \end_layout \begin_layout Subsection \family typewriter Operations and Operators \end_layout \begin_layout Standard \family typewriter The operations known to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are presented in the form of the table. Operations are subdivided into six groups separated by horizontal lines. Operations in each group have equal level of precedence and the precedence level decreases from the top to the bottom of the table. As in usual mathematical notation we can use brackets \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash verb"( )" \end_layout \end_inset to change operation precedence. \end_layout \begin_layout Standard \family typewriter Other constructions which can be used in expression are described below. \end_layout \begin_layout Standard \family typewriter \begin_inset Float table wide false sideways false status open \begin_layout Standard \align center \family typewriter \begin_inset Tabular <lyxtabular version="3" rows="22" columns="3"> <features rotate="0" tabularvalignment="middle" tabularwidth="0pt"> <column alignment="center" valignment="top"> <column alignment="center" valignment="top"> <column alignment="center" valignment="top"> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \family default \series bold Operation \family typewriter \series default \shape default \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \family default \series bold Description \family typewriter \series default \shape default \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \family default \series bold Grouping \family typewriter \series default \shape default \end_layout \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter [ \begin_inset Formula $v_1$ \end_inset , \begin_inset Formula $v_2$ \end_inset ] \family typewriter \series default \shape default \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Vector bracket \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter @ \family typewriter \series default \shape default \begin_inset Formula $x$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Holonomic vector \begin_inset Formula $\partial_x$ \end_inset \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter d \family typewriter \series default \shape default \begin_inset Formula $a$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Exterior differential \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter d \family typewriter \series default \shape default \begin_inset Formula $\omega$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> <cell alignment="center" valignment="top" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter d \family typewriter \series default \shape default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset Formula $a$ \end_inset \begin_inset Formula $\Leftrightarrow$ \end_inset (d( \family typewriter \series default \shape default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset Formula $a$ \end_inset )) \family typewriter \series default \shape default \end_layout \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dd \end_layout \end_inset \family typewriter \series default \shape default \begin_inset Formula $a$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Dualization \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dd \end_layout \end_inset \family typewriter \series default \shape default \begin_inset Formula $\omega$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> <cell alignment="none" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \family typewriter \series default \shape default \begin_inset Formula $e$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Complex conjugation \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $a_1$ \end_inset ** \family typewriter \series default \shape default \begin_inset Formula $a_2$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Exponention \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $a_1$ \end_inset ˖̂ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $a_2$ \end_inset \family typewriter \series default \shape default \end_layout \end_inset </cell> <cell alignment="center" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> <cell alignment="none" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $e$ \end_inset \begin_inset space \space{} \end_inset / \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $a$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Division \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $e$ \end_inset / \family typewriter \series default \shape default \begin_inset Formula $a_1$ \end_inset / \family typewriter \series default \shape default \begin_inset Formula $a_2$ \end_inset \begin_inset Formula $\Leftrightarrow$ \end_inset ( \family typewriter \series default \shape default \begin_inset Formula $e$ \end_inset / \family typewriter \series default \shape default \begin_inset Formula $a_1$ \end_inset )/ \family typewriter \series default \shape default \begin_inset Formula $a_2$ \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $a$ \end_inset \begin_inset space \space{} \end_inset * \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $e$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Multiplication \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $v$ \end_inset \begin_inset space \space{} \end_inset | \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $a$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Vector acting on scalar \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $v$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ii \end_layout \end_inset \begin_inset Formula $\omega_1$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset Formula $\omega_2$ \end_inset * \family typewriter \series default \shape default \begin_inset Formula $a$ \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $v$ \end_inset \begin_inset space \space{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ip \end_layout \end_inset \begin_inset space \space{} \end_inset \begin_inset Formula $\omega$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Interior product \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $\Updownarrow$ \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $v_1$ \end_inset \begin_inset space \space{} \end_inset . \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $v_2$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Scalar product \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $v$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ii \end_layout \end_inset ( \family typewriter \series default \shape default \begin_inset Formula $\omega_1$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset ( \family typewriter \series default \shape default \begin_inset Formula $\omega_2$ \end_inset * \family typewriter \series default \shape default \begin_inset Formula $a$ \end_inset )) \family typewriter \series default \shape default \end_layout \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $v$ \end_inset \begin_inset space \space{} \end_inset . \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $o$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> <cell alignment="none" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $o_1$ \end_inset \begin_inset space \space{} \end_inset . \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $o_2$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> <cell alignment="none" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $\omega_1$ \end_inset \begin_inset space \space{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset \begin_inset Formula $\omega_2$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Exterior product \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter + \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $e$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Prefix plus \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter - \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $e$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Prefix minus \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $e_1$ \end_inset \begin_inset space \space{} \end_inset + \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $e_2$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Addition \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $e_1$ \end_inset \begin_inset space \space{} \end_inset - \family typewriter \series default \shape default \begin_inset space \space{} \end_inset \begin_inset Formula $e_2$ \end_inset \end_layout \end_inset </cell> <cell alignment="center" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Subtraction \end_layout \end_inset </cell> <cell alignment="none" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> </lyxtabular> \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset CommandInset label LatexCommand label name "operators" \end_inset \begin_inset Caption Standard \begin_layout Plain Layout Operation and operators. Here: \begin_inset Formula $e$ \end_inset is any expression, \begin_inset Formula $a$ \end_inset is any scalar valued (algebraic) expressions, \begin_inset Formula $v$ \end_inset is any vector valued expression, \begin_inset Formula $x$ \end_inset is a coordinate, \begin_inset Formula $o$ \end_inset is any 1-form valued expression, \begin_inset Formula $\omega$ \end_inset is any form valued expression. \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Variables and Functions \end_layout \begin_layout Standard \family typewriter Operator listed in the table 2.2 act on the following types of the operands: \end_layout \begin_layout Itemize \family typewriter \begin_inset Argument item:1 status collapsed \begin_layout Standard \family typewriter (i) \end_layout \end_inset integer numbers (e.g. 0 \family typewriter \series default \shape default , 123 \family typewriter \series default \shape default ), \end_layout \begin_layout Itemize \family typewriter \begin_inset Argument item:1 status collapsed \begin_layout Standard \family typewriter (ii) \end_layout \end_inset symbols or identifiers (e.g. I \family typewriter \series default \shape default , phi \family typewriter \series default \shape default , RIM0103 \family typewriter \series default \shape default ), \end_layout \begin_layout Itemize \family typewriter \begin_inset Argument item:1 status collapsed \begin_layout Standard \family typewriter (iii) \end_layout \end_inset functional expressions (e.g. SIN(x) \family typewriter \series default \shape default , G(0,1) \family typewriter \series default \shape default etc). \end_layout \begin_layout Standard \family typewriter Valid identifier must belong to one of the following types: \end_layout \begin_layout Itemize \family typewriter Coordinate. \end_layout \begin_layout Itemize \family typewriter User-defined or built-in constant. \end_layout \begin_layout Itemize \family typewriter Function declared with the implicit dependence list. \end_layout \begin_layout Itemize \family typewriter Component of an object. \end_layout \begin_layout Standard \family typewriter Any valid functional expression must belong to one of the following types: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash itemsep \end_layout \end_inset =0.5mm \end_layout \begin_layout Itemize \family typewriter User-defined function. \end_layout \begin_layout Itemize \family typewriter Function defined in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset (operator). \end_layout \begin_layout Itemize \family typewriter Component of built-in or user-defined object in functional notation. \end_layout \begin_layout Itemize \family typewriter Some special functional expressions listed below. \end_layout \begin_layout Subsection \family typewriter Derivatives \end_layout \begin_layout Standard \family typewriter The derivatives in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset are written as \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset DF( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the differentiated expression, \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the differentiation variable and integer number \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the repetition of the differentiation. For example \begin_inset Formula \[ \mbox{\tt DF(f(x,y),x,2,y)}=\frac{\partial^3f(x,y)}{\partial^2x\partial y} \] \end_inset \end_layout \begin_layout Standard \family typewriter There are also another type of derivatives \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset DFP( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See section \begin_inset CommandInset ref LatexCommand ref reference "genfun" plural "false" caps "false" noprefix "false" \end_inset about the generic functions. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset They are valid only after Generic Function \family typewriter \series default \shape default declaration if the package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset dfpart \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is installed on your system. \end_layout \begin_layout Subsection \family typewriter Complex Conjugation \end_layout \begin_layout Standard \family typewriter Symbol \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset in the sum of terms is an abbreviation: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset Formula $e$ \end_inset + \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset space \space{} \end_inset \begin_inset Formula $=$ \end_inset \begin_inset space \space{} \end_inset \begin_inset Formula $e$ \end_inset + \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset Formula $e$ \end_inset \begin_inset Newline newline \end_inset \begin_inset Formula $e$ \end_inset - \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset space \space{} \end_inset \begin_inset Formula $=$ \end_inset \begin_inset space \space{} \end_inset \begin_inset Formula $e$ \end_inset - \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset Formula $e$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Functions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Re \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Im \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset gives real and imaginary parts of an expression: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Re( \begin_inset Formula $e$ \end_inset ) \begin_inset space \space{} \end_inset \begin_inset Formula $=$ \end_inset \begin_inset space \space{} \end_inset ( \begin_inset Formula $e$ \end_inset + \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset Formula $e$ \end_inset )/2 \begin_inset Newline newline \end_inset Im( \begin_inset Formula $e$ \end_inset ) \begin_inset space \space{} \end_inset \begin_inset Formula $=$ \end_inset \begin_inset space \space{} \end_inset I*(- \begin_inset Formula $e$ \end_inset + \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cc \end_layout \end_inset \begin_inset Formula $e$ \end_inset )/2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Sums and Products \end_layout \begin_layout Standard \family typewriter The following expressions represent sum and product \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Sum( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset Newline newline \end_inset Prod( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the summed expression and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines summation variables. The range of summation can be \begin_inset CommandInset label LatexCommand label name "iter" \end_inset specified by two methods. First \begin_inset Quotes eld \end_inset long \begin_inset Quotes erd \end_inset notation is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset low \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset .. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset up \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and the identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset runs from \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset low \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset up to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset up \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Both \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset low \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset up \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be given by arbitrary expressions but value of these expressions must be integer. The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset low \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be omitted \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset up \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and in this case \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset runs from 0 to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset up \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset should not coincide with any built-in or user-defined variable. \end_layout \begin_layout Standard \family typewriter In \begin_inset Quotes eld \end_inset short \begin_inset Quotes erd \end_inset notation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is just identifier \begin_inset CommandInset label LatexCommand label name "siter" \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and its range is determined using the following rules \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{list} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset Formula $\bullet$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash labelwidth \end_layout \end_inset =4mm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash leftmargin \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parindent \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Mixed letter-digit \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset runs from 0 to \begin_inset Formula $d-1$ \end_inset where \begin_inset Formula $d$ \end_inset is the space dimensionality. \end_layout \begin_layout Verbatim Aid j2s \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset consisting of lower-case letters runs from \begin_inset Formula $0$ \end_inset to \begin_inset Formula $d-1$ \end_inset \end_layout \begin_layout Verbatim j a abc kkk \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset consisting of upper-case letters runs from \begin_inset Formula $0$ \end_inset to the number of letters in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , e.g. the following identifiers run from 0 to 1 and from 0 to 3 respectively \end_layout \begin_layout Verbatim B ABC \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Letters with one trailing digit run from 0 to the value of this digit. Both \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset below runs from 0 to 3: \end_layout \begin_layout Verbatim j3 A3 \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Letters with two digits run from the value of the first digit to the value of the second digit. The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset below run from 2 to 3: \end_layout \begin_layout Verbatim j23 A23 \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Letters with 3 or more digits are incorrect \end_layout \begin_layout Verbatim j123 \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{list} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Two or more summation parameters are separated either by commas or by one of the relational operators \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter < > <= => \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter This means that only the terms satisfying these relations will be included in the sum. For example \begin_inset Formula \[ \mbox{\tt Sum(i24<=ABC,k=1..d-1,f(i24,ABC,k))} = \sum_{i=2}^{4} \sum_{\scriptstyle a=0\atop\scriptstyle i\leq a}^{3} \sum^{d-1}_{k=1} f(i,a,k) \] \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{5mm} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset 's \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sum \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Prod \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset Use \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SUM \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset PROD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset sum \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset prod \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset depending on \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset internal case as explained on page \begin_inset CommandInset ref LatexCommand pageref reference "case" plural "false" caps "false" noprefix "false" \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset should not be confused with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset 's \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SUM \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset PROD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset which are also available in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset 's \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sum \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset apply to any scalar, vector or form-valued expressions and always expanded by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset into the appropriate explicit sum of terms. On the contrary \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SUM \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defined in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset can be applied to the algebraic expressions only. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset leaves such expression unchanged and passes it to the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset algebraic evaluator. Unlike \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sum \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset the summation limits in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SUM \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be given by algebraic expressions. If value of these expressions is integer then result of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SUM \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset will be the same as for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sum \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset but if summation limits are symbolic sometimes \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset is capable to find a closed expression for such a sum but not always. See the following example \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- Function f; <- Constants n, m; <- Sum(k=1..3,f(k)); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset f(3) + f(2) + f(1) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- SUM(f(n),n,1,3); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset f(3) + f(2) + f(1) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- SUM(n,n,1,m); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset m*(m + 1) ———– 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- SUM(f(n),n,1,m); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset SUM(f(n),n,1,m) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset Newpage newpage \end_inset \end_layout \begin_layout Subsection \family typewriter Einstein Summation Rule \end_layout \begin_layout Standard \family typewriter According to the Einstein summation rule if \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset encounters some unknown repeated identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset then summation over this \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset id \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is performed. The range of the summation variable is determined according to the \begin_inset Quotes eld \end_inset short \begin_inset Quotes erd \end_inset notation explained in the previous section. \end_layout \begin_layout Subsection \family typewriter Object Components and Index Manipulation \end_layout \begin_layout Standard \family typewriter The components of built-in or user-defined object can be denoted in expressions by two methods which are similar to the notation used in the left-hand side of the assignment command. The first method uses the object identifier with additional digits denoting the indices T0 \family typewriter \series default \shape default , RIM0213 \family typewriter \series default \shape default . The second method uses the functional notation T(0) \family typewriter \series default \shape default , RIM(0,2,1,3) \family typewriter \series default \shape default , OMEGA(j,k) \family typewriter \series default \shape default . \end_layout \begin_layout Standard \family typewriter In functional notation the default index type and position \begin_inset Index idx status collapsed \begin_layout Plain Layout Index manipulations \end_layout \end_inset can be changed using the markers: ' \family typewriter \series default \shape default upper frame, . \family typewriter \series default \shape default lower frame, ˖̂ \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset upper holonomic, _ \family typewriter \series default \shape default lower holonomic. For example expression RIM(a,b,m,n) \family typewriter \series default \shape default gives components of Riemann tensor with the default indices \begin_inset Formula $R^a{}_{bmn}$ \end_inset (first upper frame and three lower frame indices) while expression RIM('a,'b,_m,_n) \family typewriter \series default \shape default gives \begin_inset Formula $R^{ab}{}_{\mu\nu}$ \end_inset with two upper frame and two lower coordinate indices. For enumerating indices position markers are ignored and only ' \family typewriter \series default \shape default and . \family typewriter \series default \shape default works for spinorial indices. \end_layout \begin_layout Standard \family typewriter In the spinorial formalism \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset spinors \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset about spinorial formalism. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset each frame index can be replaced by a pair if spinorial indices according to the formulas: \begin_inset Formula \[ A^a\sigma_a{}^{B\dot{D}}=A^{B\dot{D}},\qquad B_a\sigma^a\!{}_{B\dot{D}}=B_{B\dot{D}} \] \end_inset Accordingly any frame index can be replaced by a pair of spinorial indices. \begin_inset CommandInset label LatexCommand label name "sumspin" \end_inset Similarly one summed spinorial index or rank \begin_inset Formula $n$ \end_inset can be replaced by \begin_inset Formula $n$ \end_inset single spinor indices. There is only one restriction. If an object has several frame and/or summed spinorial indices then \emph on all \emph default must be represented in such expanded form. In the following example the null frame \begin_inset Formula $\theta^a$ \end_inset is printed in the usual and spinorial \begin_inset Formula $\theta^{B\dot C}$ \end_inset representations. The relationship \begin_inset Formula $\theta^a\sigma_a{}^{B\dot C}-\theta^{B\dot C}=0$ \end_inset is verifies as well \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates u, v, z, z \begin_inset space ~ \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset z & z \begin_inset space ~ \end_inset - conjugated pair. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Null Metric; <- Frame T(a)=d x(a); <- ds2; \begin_inset Newpage newpage \end_inset 2 ds = (-2) d u d v + 2 d z d z \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- T(a); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset a=0 : d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset a=1 : d v \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset a=2 : d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset a=3 : d z \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- T(B,C); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset B=0 C=0 : d v \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset B=0 C=1 : d z \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset B=1 C=0 : d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset B=1 C=1 : d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- T(a)*sigmai(a,B,C)-T(B,C); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 0 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Parts of Equations and Solutions \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Equations!in expressions \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The functional expressions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset LHS( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset eqcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset Newline newline \end_inset RHS( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset eqcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset give access to the left-hand and right-hand side of an equation respectively. Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset eqcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the component of the equation as explained in the previous section. \end_layout \begin_layout Standard \family typewriter The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset LHS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset RHS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset also provide access to the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset 'th \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "solutions" plural "false" caps "false" noprefix "false" \end_inset about solutions. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset solution if \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset eqcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sol( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Subsection \family typewriter Lie Derivatives \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Lie derivatives \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The Lie derivative is given by the expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Lie( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset v \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset objcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset objcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the component of an object in functional notation. For example the following expression is the Lie derivative of the metric \begin_inset Formula $\pounds_vg_{ab}$ \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Lie(vec,G(a,b)); \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The index manipulations in the Lie derivatives are permitted. In particular the expression \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Lie(vec,G(m,b)); \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter is the Lie derivative of the frame \begin_inset Formula $\pounds_vg^\mu{}_{b} \equiv \pounds_vh^\mu_a$ \end_inset and must vanish. \end_layout \begin_layout Subsection \family typewriter Covariant Derivatives and Differentials \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Covariant derivatives \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Covariant differentials \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "cder" \end_inset \end_layout \begin_layout Standard \family typewriter The covariant differential \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Dc( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset objcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \shape up \shape default , \shape default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset conn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and covariant derivative \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Dfc( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset v \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset objcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \shape up \shape default , \shape default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset conn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset objcomp \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is an object component in functional notation and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset v \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is a vector-valued expression. The optional parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset conn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are the identifiers of connections. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "conn" plural "false" caps "false" noprefix "false" \end_inset about the built-in connections. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset If \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset conn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is omitted then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset uses default connection for each type of indices: frame, coordinate, spinor and conjugated spinor. If \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset conn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is indicated then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset uses this connection instead of default one for appropriate type of indices. For example expression \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Dc(OMEGA(a,b)) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter is the covariant differential of the curvature 2-form \begin_inset Formula $D\Omega^a{}_b$ \end_inset . This expression should vanish in Riemann space and should be proportional to the torsion in Riemann-Cartan space. Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset will use default object Frame connection \family typewriter \series default \shape default (id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset omega \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ). The expression \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Dc(OMEGA(a,b),romega) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter is similar but it uses another built-in connection Riemann frame connection \family typewriter \series default \shape default (id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset romega \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) which are different if torsion or nonmetricity are nonzero. The index manipulations are allowed in the covariant derivatives. For example the expression \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Dfc(v,RIC(m̂,_n)) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter gives the covariant derivative of the curvature of the Ricci tensor with first coordinate upper and second coordinate lower indices \begin_inset Formula $\nabla_vR^\mu{}_\nu$ \end_inset . \end_layout \begin_layout Subsection \family typewriter Symmetrization \end_layout \begin_layout Standard \family typewriter The functional expressions works iff the switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset EXPANDSYM \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset EXPANDSYM \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is on \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Asy( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset i \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset Newline newline \end_inset Sy( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset i \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset Newline newline \end_inset Cy( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset i \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset They produce antisymmetrization, symmetrization and cyclic symmetrization of the expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with respect to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset i \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset without corresponding \begin_inset Formula $1/n$ \end_inset or \begin_inset Formula $1/n!$ \end_inset . \end_layout \begin_layout Subsection \family typewriter Substitutions \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Substitutions \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "subs" \end_inset \end_layout \begin_layout Standard \family typewriter The expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset SUB( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sub \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is similar to the analogous expression in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset with two generalizations: (i) it applies not only to algebraic but to form and vector valued expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset as well, \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "solutions" plural "false" caps "false" noprefix "false" \end_inset about solutions. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (ii) as in Let \family typewriter \series default \shape default command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sub \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be either the relation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset l \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset = \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset r \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \family typewriter \series default \shape default or solution Sub( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \family typewriter \series default \shape default . \end_layout \begin_layout Subsection \family typewriter Conditional Expressions \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Conditional expressions \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Boolean expressions \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The conditional expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset If( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset cond \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset chooses \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset e2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset depending on the value of the boolean expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset cond \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter Boolean expression appears in (i) the conditional expression \begin_inset CommandInset label LatexCommand label name "bool" \end_inset If \family typewriter \series default \shape default , (ii) in For all Such That \family typewriter \series default \shape default substitutions. Any nonzero expression is considered as \family default \series bold true \family typewriter \series default \shape default and vanishing expression as \family default \series bold false \family typewriter \series default \shape default . Boolean expressions may contain the following usual relations and logical operations: < > <= >= = |= not and or \family typewriter \series default \shape default . They also may contain the following predicates \begin_inset VSpace 2mm* \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset Tabular <lyxtabular version="3" rows="6" columns="2"> <features rotate="0" tabularvalignment="middle" tabularwidth="0pt"> <column alignment="left" valignment="top"> <column alignment="left" valignment="top"> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter OBJECT( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset obj \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Is \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset obj \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset an object identifier or not \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter ON( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Test position of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter OFF( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset switch \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \end_layout \end_inset </cell> <cell alignment="none" valignment="top" rightline="true" usebox="none"> \begin_inset Text \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter ZERO( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Is the value of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset zero or not \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter HASVALUE( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Whether the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset has any value or not \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter NULLM( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \end_layout \end_inset </cell> <cell alignment="left" valignment="top" topline="true" bottomline="true" rightline="true" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Is the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset the standard null metric \end_layout \end_inset </cell> </row> </lyxtabular> \end_inset \begin_inset VSpace 2mm* \end_inset \begin_inset Newline newline \end_inset Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is an object identifier. \end_layout \begin_layout Standard \family typewriter The expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ERROR( \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset message \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset causes an error with the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset message \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . It can be used to test any required conditions during the batch file execution. \end_layout \begin_layout Subsection \family typewriter Functions in Expressions \end_layout \begin_layout Standard \family typewriter Any function which appear in expression must be either declared by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Function \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset declaration or be defined in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset (in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset functions are called operators). In general arguments of functions in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset must be algebraic expression with one exception. If one (and only one) argument of some function \begin_inset Formula $f$ \end_inset is form-valued \begin_inset Formula $\omega=a d x + b d y$ \end_inset then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset applies \begin_inset Formula $f$ \end_inset to the algebraic multipliers of the form \begin_inset Formula $f(\omega) = f(a) d x+ f(b) d y$ \end_inset . The same rule works for vector-valued arguments. Let us consider the example in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash \end_layout \begin_layout Plain Layout \end_layout \end_inset operator \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset LIMIT \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is applied to the form-valued expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- www=(x+y)2̂/(x2̂-1)*d x+(x+y)/(x-z)*d y; <- www; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 x + 2*x*y + y x + y (—————–) d x + (——-) d y 2 x - z x - 1 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- LIMIT(www,x,INFINITY); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset d x + d y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter I would like to remind also that depending on the particular \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset system \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset operators must be used in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset in upper \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset LIMIT \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or lower case \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset limit \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . See page \begin_inset CommandInset ref LatexCommand pageref reference "case" plural "false" caps "false" noprefix "false" \end_inset for more details. \end_layout \begin_layout Standard \family typewriter Any function or operator defined in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset package can be used in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset as well. Some examples are considered in section \begin_inset CommandInset ref LatexCommand ref reference "packages" plural "false" caps "false" noprefix "false" \end_inset . \end_layout \begin_layout Subsection \family typewriter Expression Evaluation \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Expression evaluation \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset evaluates expressions in several steps: \end_layout \begin_layout Standard \family typewriter (1) All \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset -specific constructions such as \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sum \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Prod \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Re \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Im \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset etc are explicitly expanded. \end_layout \begin_layout Standard \family typewriter (2) If expression contains components of some built-in or user defined object they are replaced by the appropriate value. If the object is in indefinite state \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "find" plural "false" caps "false" noprefix "false" \end_inset about the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (no value of the object is known) then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset tries to calculate its value by the method used by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. The automatic object calculation can be prevented by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset AUTO \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset turning the switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset AUTO \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset off. If due to some reason the object cannot be calculated then expression evaluation is terminated with the error message. \end_layout \begin_layout Standard \family typewriter (3) After all object components are replaced by their values \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset performs all \begin_inset Quotes eld \end_inset geometrical \begin_inset Quotes erd \end_inset operations: exterior and interior products, scalar products etc. If expression is form-valued when it is reduced to the form \begin_inset Formula $a\,dx^0\wedge dx^1\dots+b\,d x^1\wedge+\dots$ \end_inset where \begin_inset Formula $a$ \end_inset and \begin_inset Formula $b$ \end_inset are algebraic expressions (similarly for the vector-valued expressions). \end_layout \begin_layout Standard \family typewriter (4) The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset algebraic simplification routine is applied to the algebraic expressions \begin_inset Formula $a$ \end_inset , \begin_inset Formula $b$ \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset In the anholonomic mode the basis \begin_inset Formula $b^i\wedge b^j\dots$ \end_inset is used instead. See section \begin_inset CommandInset ref LatexCommand ref reference "amode" plural "false" caps "false" noprefix "false" \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Final expression consist of exterior products of basis coordinate differentials \begin_inset Formula $dx^i\wedge dx^j\dots$ \end_inset (or basis vectors \begin_inset Formula $\partial_{x^i}$ \end_inset ) multiplied by the algebraic expressions. The algebraic expressions contain only the coordinates, constants and functions. \end_layout \begin_layout Subsection \family typewriter Controlling Expression Evaluation \end_layout \begin_layout Standard \family typewriter There are many \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset switches which control algebraic expression evaluation. The number of these switches and details of their work depend on the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset version. Here we consider some of these switches. All examples below are made with the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset 3.5. On other \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset versions result may be a bit different. \end_layout \begin_layout Standard \family typewriter Switches EXP \family typewriter \series default \shape default and MCD \family typewriter \series default \shape default control expansion and reduction of rational expressions to a common denominator respectively. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- (x+y)2̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 x + 2*x*y + y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off EXP; <- (x+y)2̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 (x + y) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On EXP; <- 1/x+1/y; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset x + y ——- x*y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off MCD; <- 1/x+1/y; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset -1 -1 x + y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset These switches are normally on. \end_layout \begin_layout Standard \family typewriter Switches PRECISE \family typewriter \series default \shape default and REDUCED \family typewriter \series default \shape default control evaluation of square roots: \begin_inset CommandInset label LatexCommand label name "PRECISE" \end_inset \begin_inset CommandInset label LatexCommand label name "REDUCED" \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- SQRT(-8*x2̂*y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2*SQRT( - 2*y)*x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On REDUCED; <- SQRT(-8*x2̂*y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2*SQRT(y)*SQRT(2)*I*x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off REDUCED; <- On PRECISE; <- SQRT(-8*x2̂*y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2*SQRT(y)*SQRT(2)*I*x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On REDUCED, PRECISE; <- SQRT(-8*x2̂*y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2*SQRT(y)*SQRT(2)*ABS(x) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Combining rational expressions the system by default calculates the least common multiple of denominators but turning the switch LCM \family typewriter \series default \shape default off prevents this calculation. \end_layout \begin_layout Standard \family typewriter Switch GCD \family typewriter \series default \shape default (normally off) makes the system search and cancel the greatest common divisor of the numerator and denominator of rational expressions. Turning GCD \family typewriter \series default \shape default on may significantly slow down the calculations. There is also another switch EZGCD \family typewriter \series default \shape default which uses other algorithm for g.c.d. calculation. \end_layout \begin_layout Standard \family typewriter Switches COMBINELOGS \family typewriter \series default \shape default and EXPANDLOGS \family typewriter \series default \shape default control the evaluation of logarithms \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- On EXPANDLOGS; <- LOG(x*y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset LOG(x) + LOG(y) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- LOG(x/y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset LOG(x) - LOG(y) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off EXPANDLOGS; <- On COMBINELOGS; <- LOG(x)+LOG(y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset LOG(x*y) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter By default all polynomials are considered by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset as the polynomials with integer coefficients. The switches RATIONAL \family typewriter \series default \shape default and COMPLEX \family typewriter \series default \shape default allow rational and complex coefficients in polynomials respectively: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- (x2̂+y2̂+x*y/3)/(x-1/2); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 2*(3*x + x*y + 3*y ) ———————– 3*(2*x - 1) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On RATIONAL; <- (x2̂+y2̂+x*y/3)/(x-1/2); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 1 2 x + —*x*y + y 3 ——————- 1 x - — 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off RATIONAL; <- 1/I; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 1 — I \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- (x2̂+y2̂)/(x+I*y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 x + y ——— I*y + x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On COMPLEX; <- 1/I; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset - I \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- (x2̂+y2̂)/(x+I*y); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset x - I*y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Switch RATIONALIZE \family typewriter \series default \shape default removes complex numbers from the denominators of the expressions but it works even if COMPLEX \family typewriter \series default \shape default is off. \end_layout \begin_layout Standard \family typewriter Turning off switch EXP \family typewriter \series default \shape default and on GCD \family typewriter \series default \shape default one can make the system to factor expressions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Off EXP; <- On GCD; <- x2̂+y2̂+2*x*y; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 (x + y) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Similar effect can be achieved by turning on switch FACTOR \family typewriter \series default \shape default . Unfortunately this works only when \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset prints expressions and internally expressions remain in the expanded form. To make \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset to work with factored expressions internally one must turn on FACTOR \family typewriter \series default \shape default and AEVAL \family typewriter \series default \shape default . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset AEVAL \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset switch AEVAL \family typewriter \series default \shape default make \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset to use an alternative \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset routine for algebraic expression evaluation and simplification. This routine works well with FACTOR \family typewriter \series default \shape default on. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See section \begin_inset CommandInset ref LatexCommand ref reference "tuning" plural "false" caps "false" noprefix "false" \end_inset about configuration files. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Possibly it is good idea to turn switch AEVAL \family typewriter \series default \shape default on by default. This can be done using \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset configuration files. \end_layout \begin_layout Subsection \family typewriter Substitutions \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Substitutions \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The substitution commands in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset are the same as the corresponding \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset instructions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Let \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Match \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset For All Let \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset For All \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Such That \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset cond \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Let \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sub \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset For All \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Such That \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset cond \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Match \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sub \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "solutions" plural "false" caps "false" noprefix "false" \end_inset about solutions. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sub \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is either relation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset l \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset = \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset r \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \family typewriter \series default \shape default or the solution in the form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sol( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . After the substitution is activated every appearance of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset l \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset will be replaced by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset r \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The For All \family typewriter \series default \shape default substitutions have additional list of parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and will work for any value of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The optional condition \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset cond \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset imposes restrictions on the value of the parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset cond \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the boolean expression (see page \begin_inset CommandInset ref LatexCommand pageref reference "bool" plural "false" caps "false" noprefix "false" \end_inset ). \end_layout \begin_layout Standard \family typewriter The substitution can be deactivated by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Clear \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset For All \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space \thinspace{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Such That \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset cond \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Clear \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset sub \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Notice that the variables \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset must be exactly the same as in the corresponding For All Let \family typewriter \series default \shape default command. \end_layout \begin_layout Standard \family typewriter The difference between \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Match \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Let \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is that the former matches the degrees of the expressions exactly while \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Let \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset matches all powers which are greater than one indicated in the substitution: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Const a; <- (a+1)8̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 8 7 6 5 4 3 2 a + 8*a + 28*a + 56*a + 70*a + 56*a + 28*a + 8*a + 1 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Let a3̂=1; <- (a+1)8̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 85*a + 86*a + 85 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Clear a3̂; <- Match a3̂=1; <- (a+1)8̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 8 7 6 5 4 2 a + 8*a + 28*a + 56*a + 70*a + 28*a + 8*a + 57 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Substitutions can be used for various purposes, for example: (i) to define additional mathematical relations such as trigonometric ones; (ii) to \begin_inset Quotes eld \end_inset assign \begin_inset Quotes erd \end_inset value to the user-defined and built-in constants; (iii) to define differentiation rules for functions. \end_layout \begin_layout Standard \family typewriter After some substitution is activated it applies to every evaluated expression but value of the objects calculated \emph on before \emph default remain unchanged. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset re-simplifies the value of the object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the object name, or identifier, or the group object name. Let us consider a simple \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task which calculates the volume 4-form of some metric \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- Constant a; <- Tetrad T0=d t, T1=d x, T2=SIN(a)*d y+COS(a)*d z, T3=-COS(a)*d y+SIN(a)* d z; <- Find and Write Volume; Volume : \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 VOL = (SIN(a) + COS(a) ) d t \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset We see that \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset do not know the appropriate trigonometric rule. Thus we are going to apply substitution \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- For all x let SIN(x)2̂ = 1-COS(x)2̂; <- Write Volume; Volume : \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset VOL = d t \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset The situation has been improved. But actually, the \emph on internal \emph default representation of VOL \family typewriter \series default \shape default remains unchanged. Write \family typewriter \series default \shape default by default re-simplifies expressions before printing. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swinda{ \end_layout \end_inset WRS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset By turning switch WRS \family typewriter \series default \shape default off we can prevent this re-simplification: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Off WRS; <- Write Volume; Volume : 2 2 VOL = (SIN(a) + COS(a) ) d t \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Now we can apply \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset : \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Evaluate Volume; <- Write Volume; Volume : \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset VOL = d t \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d x \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset space \space{} \end_inset d z \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset We see that the internal value of VOL \family typewriter \series default \shape default now has been replaced by re-simplified expression. \end_layout \begin_layout Standard \family typewriter Notice that the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Evaluate All; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset applies \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to all objects whose value is currently known. \end_layout \begin_layout Subsection \family typewriter Generic Functions \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Generic Functions \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "genfun" \end_inset \end_layout \begin_layout Standard \family typewriter Unfortunately \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset lacks the notion of partial derivative of a function. The expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset DF(f(x,y),x) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is treated by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset as the \begin_inset Quotes eld \end_inset derivative of the expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset f(x,y) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with respect to the variable \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset x \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Quotes erd \end_inset rather than the \begin_inset Quotes eld \end_inset derivative of the function \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset f \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with respect to its first argument \begin_inset Quotes erd \end_inset . Due to this \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset cannot handle chain differentiation rule etc. This problem is fixed by the package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset dfpart \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset written by H. \begin_inset space ~ \end_inset Melenk. This package introduces notion of generic function and partial derivative \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset DFP \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . If \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset dfpart \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is installed on your \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset system \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset provides the interface to these facilities. \end_layout \begin_layout Standard \family typewriter Let us consider an example. First we declare one usual and two generic functions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- Function f; <- Generic Function g(a,b), h(b); <- Write Functions; Functions: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset g*(a,b) h*(b) f \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Generic functions must be always declared with the list of parameters ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset b \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset in our example). These parameters play the role of labels which denotes arguments of the generic function and the partial derivatives with respect to these arguments are defined. Due to this generic functions allow the chain differentiation rule \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- DF(f(SIN(x),y),x); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset DF(f(SIN(x),y),x) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- DF(g(SIN(x),y),x); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset COS(x)*g (SIN(x),y) a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset Here subscript \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset denotes the derivative of the function \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with respect to the first argument. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{5mm} \end_layout \end_inset The operator \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset DFP \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is introduced to denotes such derivatives in expressions: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- DF(g(x,y)*h(y),b); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 0 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- DFP(g(x,y)*h(y),b); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset g (x,y)*h(y) + h (y)*g(x,y) b b \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset Newpage newpage \end_inset \end_layout \begin_layout Standard \family typewriter If switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset DFPCOMMUTE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset DFPCOMMUTE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is turned on then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset DFP \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset derivatives commute. \end_layout \begin_layout Section \family typewriter Using Built-in Formulas In Calculations \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset has large number of built-in objects and almost each object has built-in formulas or so called \emph on ways of calculation \emph default which can be used to find the value of the object. This section explains how these formulas (ways) can be used. \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Command \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Ways of calculation \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "find" \end_inset \end_layout \begin_layout Standard \family typewriter Almost each \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset built-in object has associated \emph on ways of calculation \emph default . Each way is nothing but a formula or equation which allows to compute the value of the object. All these formulas are described in the usual mathematical style in chapter 3. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or equivalently \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset ? \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints information about object's ways of calculation. \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset applies built-in formulas to calculate the object value \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset way \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the object name, or identifier, or group object name. The optional specification \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset way \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset indicates the particular way if the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset has several built-in ways of calculation. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{3mm} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Consider the curvature 2-form \begin_inset Formula $\Omega^a{}_b$ \end_inset (object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Curvature \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset OMEGA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ): \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Show Curvature; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Curvature OMEGA'a.b is 2-form Value: unknown Ways of calculation: Standard way (omega) From spinorial curvature (OMEGAU*,OMEGAD) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \noindent \family typewriter We can see that this object has two built in ways of calculation. First way named Standard way \family typewriter \series default \shape default is the usual equation \begin_inset Formula $\Omega^a{}_b=d\omega^a{}_b+\omega^a{}_m\wedge\omega^m{}_b$ \end_inset . Second way under the name From spinorial curvature \family typewriter \series default \shape default uses spinor \begin_inset Formula $\tsst$ \end_inset tensor relationship to compute the curvature 2-form using its spinor analogues \begin_inset Formula $\Omega_{AB}$ \end_inset and \begin_inset Formula $\Omega_{\dot{A}\dot{B}}$ \end_inset as the source data. The ways of calculation are printed by the command Show \family typewriter \series default \shape default in the form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset wayname \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset SI \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset wayname \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the way name and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See Eq. ( \begin_inset CommandInset ref LatexCommand ref reference "omes" plural "false" caps "false" noprefix "false" \end_inset ) on \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset omes \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset SI \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are the identifiers of the \emph on source \emph default objects which are present in the right-hand side of the equation. The value of these objects must be known before the formula can be applied. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout % \backslash enlargethispage{5mm} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset way \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command allows one to choose the particular way which can be done by two methods. In the first form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset way \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is just the name exactly as it printed by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset wayname \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or Using standard way \family typewriter \series default \shape default or By standard way \family typewriter \series default \shape default if the way name is Standard way \family typewriter \series default \shape default . Another method to specify the way is to indicate the appropriate source object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset From \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Newline newline \end_inset Using \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the name or the identifier of the source object. For example second (spinorial) way of calculation for the curvature 2-form can be chosen by the following equivalent commands \begin_inset VSpace -1mm \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find curvature from spinorial curvature; Find curvature using OMEGAU; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter while first way is activated by the commands \begin_inset VSpace -1mm* \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find curvature by standard way; Find curvature using omega; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Recall that object identifiers are case sensitive and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset omega \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the identifier of the frame connection 1-form \begin_inset Formula $\omega^a{}_b$ \end_inset and should not be confused with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset OMEGA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset way \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset specification in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be omitted and in this case \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset uses the following algorithm to choose a particular way of calculation. Observe that the identifier of the undotted curvature 2-form \begin_inset Formula $\Omega_{AB}$ \end_inset is marked by the symbol \begin_inset Formula $*$ \end_inset . This label marks so called \emph on main \emph default objects. If no way of calculation is specified when \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset tries to choose the way, browsing the way list form top to the bottom, for which the value of the \emph on main \emph default object is already known. If no switch way exists then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset just picks up the first way in the list. Therefore in our example the command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find curvature; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter will use the second way if the value of the object \begin_inset Formula $\Omega_{AB}$ \end_inset (id. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset OMEGAU \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) is known and second way otherwise. \end_layout \begin_layout Standard \family typewriter As soon as some way of calculation is chosen \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset tries to calculate the values of the source objects which are present in the right-hand side of corresponding equations. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset tries to do this by applying the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command without way specification to these objects. Thus a single \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can cause quite long chain of calculations. This recursive work is reflected by the appropriate tracing messages. The tracing can be eliminated by turning off switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset TRACE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset TRACE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Here we present the sample \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset session which computes curvature 2-form for the flat gravitational waves \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Cord u, v, z, z \begin_inset space ~ \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset z & z \begin_inset space ~ \end_inset - conjugated pair. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Null Metric; <- Function H(u,z,z \begin_inset space ~ \end_inset ); <- Frame T0=d u, T1=d v+H*d u, T2=d z, T3=d z \begin_inset space ~ \end_inset ; <- ds2; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 ds = ( - 2*H) d u + (-2) d u d v + 2 d z d z \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Find Curvature; Sqrt det of metric calculated. 0.16 sec Volume calculated. 0.16 sec Vector frame calculated From frame. 0.16 sec Inverse metric calculated From metric. 0.16 sec Frame connection calculated. 0.22 sec Curvature calculated. 0.22 sec <- Write Curvature; Curvature: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 1 OMEGA = ( - DF(H,z,2)) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z + ( - DF(H,z,z \begin_inset space ~ \end_inset )) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z \begin_inset space ~ \end_inset 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 1 OMEGA = ( - DF(H,z,z \begin_inset space ~ \end_inset )) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z + ( - DF(H,z \begin_inset space ~ \end_inset ,2)) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z \begin_inset space ~ \end_inset 3 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 OMEGA = ( - DF(H,z,z \begin_inset space ~ \end_inset )) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z + ( - DF(H,z \begin_inset space ~ \end_inset ,2)) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z \begin_inset space ~ \end_inset 0 \begin_inset Newpage newpage \end_inset 3 OMEGA = ( - DF(H,z,2)) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z + ( - DF(H,z,z \begin_inset space ~ \end_inset )) d u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d z \begin_inset space ~ \end_inset 0 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Finally we want to emphasize that ways associated with some object may depend on the concrete environment. In particular the Standard way \family typewriter \series default \shape default for the curvature 2-form is always available but second way which is essentially related to spinors works \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash pref{ \end_layout \end_inset spinors \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset about the spinorial formalism. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset only in the 4-dimensional spaces of Lorentzian signature and iff the metric is null. If some way is not valid in the current environment it simply disappears from the way list printed by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter It should be noted also that the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command works only if the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is in the indefinite state and is rejected if the value of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is already known. If you want to re-calculate the object then previous value must be cleared by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset destroys the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset value and returns it to initial indefinite state. It can be used also to free the memory. \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Zero \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Zero \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Zero \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset assigns zero values to all \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset components. \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Normalize \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Normalize \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Normalize \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset applies to equations. It replaces equalities of the form \begin_inset Formula $l=r$ \end_inset by the equalities \begin_inset Formula $l-r=0$ \end_inset and re-simplifies the result. \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Evaluate \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset re-simplifies existing value of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . This command is useful if we want to apply new substitutions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "subs" plural "false" caps "false" noprefix "false" \end_inset about substitutions. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset to the object whose value is already known. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Evaluate All; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset re-simplifies all objects whose value is currently known. \end_layout \begin_layout Section \family typewriter Printing Result of Calculations \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Command \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints value of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset id the object name or identifier. \begin_inset Index idx status collapsed \begin_layout Plain Layout Group name \end_layout \end_inset Group names denoting a collection of several objects \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "macro" plural "false" caps "false" noprefix "false" \end_inset about macro objects. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and macro object identifiers can be used in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command as well. In addition word \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset All \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can be used to print all currently known objects. \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset can print declarations as well if \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is functions \family typewriter \series default \shape default , constants \family typewriter \series default \shape default , or affine parameter \family typewriter \series default \shape default . \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space ~ \end_inset to \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or equivalently \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space ~ \end_inset > \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset writes result into the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Notice that \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset always destroys previous contents of the file. Therefore we have another command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write to \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset Newline newline \end_inset Write > \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset which redirects all output into the file. The standard output can be restored by the commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset End of Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset EndW \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset EndW; \begin_inset Newline newline \end_inset End of Write; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{3mm} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter By default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset re-simplifies the expressions before printing them. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset WRS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "subs" plural "false" caps "false" noprefix "false" \end_inset about substitutions. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset This is convenient when substitutions are activated but slows down the printing especially for very large expressions. The re-simplification can be abolished by turning off switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset WRS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . If switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset WMATR \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is turned on then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset WMATR \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset prints all 2-index scalar-valued objects in the matrix form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- On wmatr; <- Find and Write metric; Assuming Default Metric. Metric calculated By default. 0.06 sec Metric: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset [-1 0 0 0] [ ] [0 1 0 0] [ ] [0 0 1 0] [ ] [0 0 0 1] \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset prints frame, spinor and enumerating indices as numerical subscripts while holonomic indices are printed as the coordinate identifiers. If frame is holonomic and there is no difference between frame and coordinate indices then by default all frame indices are also labelled by the appropriate identifiers. But is switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset HOLONOMIC \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swinda{ \end_layout \end_inset HOLONOMIC \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is turned off they are still printed as numbers. \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Print \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Command \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Print \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command described in the previous section prints value of an object. This value must be calculated beforehand by the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Find \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command or established by the assignment. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Print \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset evaluates expression and immediately prints its value. It has several forms \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Print \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset For \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset For \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Print \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is expression to be evaluated and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset indicates that expression must be evaluated for several value of some variable. The specification \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset iter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is completely the same as is the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sum \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset expression and is described in details in section \begin_inset CommandInset ref LatexCommand ref reference "iter" plural "false" caps "false" noprefix "false" \end_inset on page \begin_inset CommandInset ref LatexCommand pageref reference "iter" plural "false" caps "false" noprefix "false" \end_inset . It consists of the list of parameters separated by commas \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or relational operators < > => =< \family typewriter \series default \shape default . For example the command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter G(a,b) for a<b; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter prints off-diagonal components of the metric. \end_layout \begin_layout Standard \family typewriter Both word \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Print \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset For \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset parts of the command can be omitted and it is possible just to enter an expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and it will be evaluated and printed. The expression can contain indefinite identifiers and by default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset treats them similarly to the variables in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset For \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset part of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Print \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. The range of such parameters are determined by the short summation variable specification as explained on page \begin_inset CommandInset ref LatexCommand pageref reference "siter" plural "false" caps "false" noprefix "false" \end_inset . For example the following four commands are equivalent. they all print the components of the holonomic metric \begin_inset Formula $g_{\alpha\beta}$ \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Print g(a,b) for a,b; For a,b Print g(a,b); g(a,b) for a,b; g(a,b); \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Here the parameters \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset b \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset run from 0 to \begin_inset Formula $d-1$ \end_inset . \end_layout \begin_layout Standard \family typewriter Unfortunately such treatment of unknown variables may create some confusion since occasionally misprinted identifier may be recognizes by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset as an iteration variable. If switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset NOFREEVARS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset NOFREEVARS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is turned on then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash \end_layout \begin_layout Plain Layout \end_layout \end_inset becomes more scrupulous and any unknown variable will cause the error. \end_layout \begin_layout Subsection \family typewriter Controlling the Output \end_layout \begin_layout Standard \family typewriter There are several switches and commands which allow one to change output form of expressions. One needs to stress that all these facilities have no influence on the \emph on internal form \emph default of expressions, they alter the \emph on printout only \emph default . \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{2mm} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Switches ALLFAC \family typewriter \series default \shape default and command Factor \family typewriter \series default \shape default control factoring of subexpressions. In the on default position ALLFAC \family typewriter \series default \shape default makes the system search for a common factor and print it outside the expression. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Factor \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Factor \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset makes the system collect together terms with different powers of subexpressions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset RemFac \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset RemFac \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset removes the action of the previous Factor \family typewriter \series default \shape default command. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Constants a,b,c; <- a*(a+b+1)2̂; \begin_inset Newpage newpage \end_inset 2 2 a*(a + 2*a*b + 2*a + b + 2*b + 1) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off ALLFAC; <- a*(a+b+1)2̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 3 2 2 2 a + 2*a *b + 2*a + a*b + 2*a*b + a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Factor b; <- a*(a+b+1)2̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 3 2 b *a + b*(2*a + 2*a) + a + 2*a + a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On ALLFAC; <- a*(a+b+1)2̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 b *a + 2*b*a*(a + 1) + a*(a + 2*a + 1) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Normally \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset prints terms in some canonical order. The switch REVPRI \family typewriter \series default \shape default prints terms in reverse order and command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Order \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Order \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset specifies the required order of subexpressions explicitly. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Constants a,b,c; <- (a+b*c)3̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 3 2 2 2 3 3 a + 3*a *b*c + 3*a*b *c + b *c \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On REVPRI; <- (a+b*c)3̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 3 3 2 2 2 3 b *c + 3*a*b *c + 3*a *b*c + a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Order c,a,b; <- (a+b*c)3̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 3 2 2 2 3 3 a + 3*c*a *b + 3*c *a*b + c *b \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off REVPRI; <- (a+b*c)3̂; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 3 3 2 2 2 3 c *b + 3*c *a*b + 3*c*a *b + a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter By default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset prints fractions in two-dimensional format but turning off switch RATPRI \family typewriter \series default \shape default prevents this facility. Switch DIV \family typewriter \series default \shape default in the on position makes the system divide each term of the numerator by the denominator and to print the denominator in the form of negative powers. Switch RAT \family typewriter \series default \shape default works in combination with the Factor \family typewriter \series default \shape default command. In the on position it makes the system divide each term collected by the Factor \family typewriter \series default \shape default in the numerator by the denominator. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Const a,b,c; <- (a+b+1)2̂/a; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 a + 2*a*b + 2*a + b + 2*b + 1 ——————————— a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off RATPRI; <- (a+b+1)2̂/a; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 (a + 2*a*b + 2*a + b + 2*b + 1)/a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On DIV; <- (a+b+1)2̂/a; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset -1 2 -1 -1 a + a *b + 2*a *b + a + 2*b + 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Factor b; <- (a+b+1)2̂/a; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 -1 -1 -1 b *a + 2*b*(a + 1) + a + a + 2 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Off DIV; <- (a+b+1)2̂/a; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 (b + 2*b*(a + 1) + a + 2*a + 1)/a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On RAT; <- (a+b+1)2̂/a; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 b /a + 2*b*(a + 1)/a + (a + 2*a + 1)/a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- On RATPRI; <- (a+b+1)2̂/a; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2 2 b a + 1 a + 2*a + 1 —- + 2*b*——- + ————– a a a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter One needs to realize that output form transformations may require a long time and memory expense. There is a special switch PRI \family typewriter \series default \shape default which allows one to minimize this expense. If PRI \family typewriter \series default \shape default is turned off then the system will print all expressions exactly in their internal form and output control does not work. This is the fastest way to print result of calculations. \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Line Length \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Line Length \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset sets the output line length to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Subsection \family typewriter \SpecialChar LaTeX \begin_inset space \space{} \end_inset and Graphics Output \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout LaTeX@\SpecialChar LaTeX \begin_inset space \space{} \end_inset output mode \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Graphics output mode \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Some versions of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset running under Windows, OS/2 or X-windows are equipped with the graphic shells which provide book-style output with Greek characters, integral signs etc. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is compatible with these systems. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset FANCY \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset This graphic regime is activated by switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset FANCY \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter Graphic output mode internally uses some subset of the \SpecialChar LaTeX \begin_inset space \space{} \end_inset language. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset LATEX \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset LATEX \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset makes \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset to print the output in the \SpecialChar LaTeX \begin_inset space \space{} \end_inset format. This output can be written into a file and later directly inserted in a document. Notice that turning off switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset LATEX \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset returns graphic output mode with switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset FANCY \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset on while turning off \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset FANCY \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset automatically turns off \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset LATEX \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset as well and returns usual character output mode. \end_layout \begin_layout Standard \family typewriter In graphic regime the derivatives are printed in \begin_inset Formula $\partial f/\partial x$ \end_inset notation. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset DFINDEXED \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset DFINDEXED \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset makes the system to print derivatives in the indexed notation \begin_inset Formula $f_x$ \end_inset . \end_layout \begin_layout Standard \family typewriter The following expressions is the scalar curvature of the Bondi metric obtained by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset and directly inserted in this manual \begin_inset Formula \begin{eqnarray*} R &= & \bigl(4\,e^{2\,\beta\,+\,2\,\gamma}\,\cos(\theta)\,\frac{\partial\,U}{\partial\,r}\,r^2\,-\,8\,e^{4\,\beta}\,\cos(\theta)\,\frac{\partial\,\beta}{\partial\,\theta}\,-\,\\ &&4\,e^{2\,\beta\,+\,2\,\gamma}\,\cos(\theta)\,\frac{\partial\,\gamma}{\partial\,r}\,U\,r^2\,+\,12\,e^{4\,\beta}\,\cos(\theta)\,\frac{\partial\,\gamma}{\partial\,\theta}\,+\,\\ &&12\,e^{2\,\beta\,+\,2\,\gamma}\,\cos(\theta)\,U\,r\,+\,4\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial^2\,U}{\partial\,r\,\partial\,\theta}\,\sin(\theta)\,r^2\,+\,\\ &&e^{4\,\gamma}\,(\frac{\partial\,U}{\partial\,r})^2\,\sin(\theta)\,r^4\,+\,4\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial\,U}{\partial\,r}\,\frac{\partial\,\beta}{\partial\,\theta}\,\sin(\theta)\,r^2\,+\,\\ &&4\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial\,U}{\partial\,\theta}\,\frac{\partial\,\gamma}{\partial\,r}\,\sin(\theta)\,r^2\,+\,12\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial\,U}{\partial\,\theta}\,\sin(\theta)\,r\,-\,\\ &&4\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial^2\,V}{\partial\,r^2}\,\sin(\theta)\,r\,-\,8\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial\,V}{\partial\,r}\,\frac{\partial\,\beta}{\partial\,r}\,\sin(\theta)\,r\,-\,\\ &&8\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial\,V}{\partial\,r}\,\sin(\theta)\,+\,8\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial^2\,\beta}{\partial\,r\,\partial\,\theta}\,\sin(\theta)\,U\,r^2\,-\,\\ &&8\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial^2\,\beta}{\partial\,r^2}\,\sin(\theta)\,V\,r\,+\,8\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial\,\beta}{\partial\,r}\,\sin(\theta)\,V\,-\,\\ &&8\,e^{4\,\beta}\,\frac{\partial^2\,\beta}{\partial\,\theta^2}\,\sin(\theta)\,-\,12\,e^{4\,\beta}\,(\frac{\partial\,\beta}{\partial\,\theta})^2\,\sin(\theta)\,+\,16\,e^{4\,\beta}\,\frac{\partial\,\beta}{\partial\,\theta}\,\frac{\partial\,\gamma}{\partial\,\theta}\,\sin(\theta)\,-\,\\ &&8\,e^{2\,\beta\,+\,2\,\gamma}\,(\frac{\partial\,\gamma}{\partial\,r})^2\,\sin(\theta)\,V\,r\,+\,8\,e^{2\,\beta\,+\,2\,\gamma}\,\frac{\partial\,\gamma}{\partial\,r}\,\frac{\partial\,\gamma}{\partial\,\theta}\,\sin(\theta)\,U\,r^2\,+\,\\ &&4\,e^{4\,\beta}\,\frac{\partial^2\,\gamma}{\partial\,\theta^2}\,\sin(\theta)\,-\,8\,e^{4\,\beta}\,(\frac{\partial\,\gamma}{\partial\,\theta})^2\,\sin(\theta)\,+\,4\,e^{4\,\beta}\,\sin(\theta)\bigr)/\\ &&\bigl(2\,e^{4\,\beta\,+\,2\,\gamma}\,\sin(\theta)\,r^2\bigr) \end{eqnarray*} \end_inset \end_layout \begin_layout Subsection \family typewriter Exporting Data Into Other Systems \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Output modes \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Capabilities of major modern computer algebra systems are approximately equivalent but not quite. One system is better in doing one things and other is better for other purposes. It may happen that tools which you need are available only in one particular systems. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset provides quite unique facility to export the data into other computer algebra systems. Turning on one of the following switches establishes the \emph on output mode \emph default in which all expressions are printed in the \emph on input \emph default language of other CAS. This output can be saved into a file and later you can use this CAS to proceed you analysis of the data. At present \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset supports five output modes which are controlled by the switches \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset MACSYMA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset MAPLE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset MATH \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset REDUCE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset GRG \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Tabular <lyxtabular version="3" rows="5" columns="2"> <features rotate="0" tabularvalignment="middle" tabularwidth="0pt"> <column alignment="left" valignment="top"> <column alignment="left" valignment="top"> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset MACSYMA \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash macsyma \end_layout \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset MAPLE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash maple \end_layout \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset MATH \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mathematica \end_layout \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset REDUCE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset GRG \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \end_layout \end_inset </cell> </row> </lyxtabular> \end_inset \begin_inset Newline newline \end_inset Notice the last switch allows one to print the data in the form which can be later inserted into \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task. \end_layout \begin_layout Section \family typewriter Advanced Facilities \end_layout \begin_layout Subsection \family typewriter Solving Equations \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Solve \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "solutions" \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset provides simple interface to the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset algebraic equation solver. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Solve \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset l \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset r \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space ~ \end_inset for \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset resolves equations \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset l \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset r \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with respect to expressions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . This command has also other form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Solve \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset equation \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset for \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset equation \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the name or identifier of some built-in or user-defined equation. Both form of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Solve \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command works with form and scalar valued equations as well but \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset must be algebraic. The resulting solutions are stored in the special object \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Solutions \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (identifier \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sol \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ). They can be printed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdindx{ \end_layout \end_inset Write \begin_inset ERT status collapsed \begin_layout Plain Layout }{ \end_layout \end_inset Solutions \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Write Solutions; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Left and right hand sides of \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset 'th solution can be used in expression as \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset LHS(Sol( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset )) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset RHS(Sol( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset )) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The expression \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Sol( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset referring to the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset 'th solution can be used in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SUB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Let \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset substitutions as well: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- Solve x2-2*x=5, y=9 for x, y; <- Write Solutions; Solutions: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Sol(0) : y = 9 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Sol(1) : x = - SQRT(6) + 1 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Sol(2) : y = 9 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset Sol(3) : x = SQRT(6) + 1 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- SUB(Sol(1),(x-1)2); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 6 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Let Sol(3); <- (x-1)2; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 6 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Solutions can be cleared by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdindx{ \end_layout \end_inset Erase \begin_inset ERT status collapsed \begin_layout Plain Layout }{ \end_layout \end_inset Solutions \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Erase Solutions; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset One need to stress that \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Solve \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is capable to solve algebraic relations only. Solving algebraic relations \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset knows already that the function \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ASIN \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is inverse to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SIN \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Inverse \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Inverse \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset tells the system that functions \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset f2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are inverse to each other. \end_layout \begin_layout Subsection \family typewriter Saving Data for Later Use \end_layout \begin_layout Standard \family typewriter \begin_inset CommandInset label LatexCommand label name "UnloadLoad" \end_inset \end_layout \begin_layout Standard \family typewriter It is very convenient to have facilities to save results of calculations in a form fitted for restoring and further manipulation. For this purpose \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset has two special commands: Unload \family typewriter \series default \shape default and Load \family typewriter \series default \shape default . \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "Unload" \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset > \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset Newline newline \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset To \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset writes \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset value into \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset in some special format. Here \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is name or identifier of an object. \end_layout \begin_layout Standard \family typewriter The data can be later restored with help of the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Load \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Load \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The command Unload \family typewriter \series default \shape default always overwrites previous \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset contents. To save several objects in one file one must use the following sequence of commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset EndU \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset End of Unload \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Unload > \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; Unload \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; Unload \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; ... Unload \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; End Of Unload; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Here command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Unload > \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset opens \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and End Of Unload; \family typewriter \series default \shape default closes it. The last command has the short form \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset EndU; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset In fact presented above sequence of commands can be abbreviated as \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space ~ \end_inset > \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter One needs to stress that only the commands Unload …; \family typewriter \series default \shape default can be used between Unload > … \family typewriter \series default \shape default and End Of Unload; \family typewriter \series default \shape default . If this rule does not hold then Load \family typewriter \series default \shape default may fail to restore the file. The only additional command which can be used among these Unload \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \family typewriter \series default \shape default commands is the comment % \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset text \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \family typewriter \series default \shape default . This command insertes the comment \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset text \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset into the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Later when \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset will be restored by the Load \family typewriter \series default \shape default the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset text \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset message will be printed. This allows one to attach comments to unreadable files produced by Unload \family typewriter \series default \shape default command. \end_layout \begin_layout Standard \family typewriter As in other commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command is either the name or identifier of an object. Names Coordinates \family typewriter \series default \shape default , Constants \family typewriter \series default \shape default and Functions \family typewriter \series default \shape default can also be used to save declarations. And finally, the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Unload All > \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset saves all objects whose value is currently known \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See section \begin_inset CommandInset ref LatexCommand ref reference "amode" plural "false" caps "false" noprefix "false" \end_inset about anholonomic basis. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and all declarations. Moreover, in the anholonomic basis mode this command saves full information about an anholonomic basis. \end_layout \begin_layout Standard \family typewriter When data or coordinates declarations are restored from a file they replace current values. Function and constant declarations are added to current declarations. \end_layout \begin_layout Standard \family typewriter One should realize that serious troubles may appear when different coordinates are used in the current session and in the restored file. Even the order of coordinates is extremely important. We strongly recommend saving all declarations (especially coordinates) in addition to other objects. It ensures at least that will \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset print a warning message if some contradictions are detected between current declarations and declarations stored into a file. The best way to avoid these troubles is to use the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Unload All > \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Loading the file saved by this command at the very beginning of a new \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset task completely restores the previous \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset state with all data and declarations. \end_layout \begin_layout Standard \family typewriter Sometimes one needs to prevent the Load \family typewriter \series default \shape default /Unload \family typewriter \series default \shape default operations with coordinates. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset UNLCORD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset If switch UNLCORD \family typewriter \series default \shape default is turned off (normally on) then all Load \family typewriter \series default \shape default and Unload \family typewriter \series default \shape default operations with coordinates are blocked. \end_layout \begin_layout Standard \family typewriter Since Unload \family typewriter \series default \shape default writes data in human-unreadable form there is the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show File \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset File \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset File \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or equivalently \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset ? \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset File \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset space ~ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset Newline newline \end_inset File \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset which prints short information about objects and declarations contained in the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . It also prints comments contained in the file. \end_layout \begin_layout Subsection \family typewriter Coordinate Transformations \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Coordinate transformations \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset New Coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset New Coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset new \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rpt{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset old \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset introduces new coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset new \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and defines how old coordinates \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset old \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are expressed in terms of new ones. If the specified transformation is nonsingular \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset converts all existing objects to the new coordinate system. \end_layout \begin_layout Standard \family typewriter The New Coordinates \family typewriter \series default \shape default command properly transforms all objects having coordinate indices. The transformation of frame indices depend on the switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset HOLONOMIC \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset HOLONOMIC \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset In general case when frame is not holonomic then objects having frame indices remain unchanged and only their components are transformed into the new coordinate system. But if frame is holonomic then by default all frame indices are transformed similarly to the coordinate ones. Notice that in such situation the frame after transformation once again will be holonomic in the new coordinate system. But if switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset HOLONOMIC \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is turned off the system distinguishes frame and coordinate indices in spite of the current frame type. In such situation the holonomic frame ceases to be holonomic after coordinate transformation. \end_layout \begin_layout Subsection \family typewriter Frame Transformations \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Frame transformations \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Spinorial rotations are performed by the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Make Spinorial Rotation \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Spinorial Rotation \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Make \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Spinorial Rotation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset (( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{00}$ \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{01}$ \end_inset ), ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{10}$ \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{11}$ \end_inset )) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where expressions \begin_inset Formula $\mbox{\parm{expr}}_{AB}$ \end_inset comprise the SL(2,C) transformation matrix \begin_inset Formula \[ \phi'_A=L_A{}^B\phi_B,\ \ \mbox{\parm{expr}}_{AB}=L_A{}^B \] \end_inset \end_layout \begin_layout Standard \family typewriter If the specified matrix is really a SL(2,C) one then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash \end_layout \begin_layout Plain Layout \end_layout \end_inset performs appropriate transformation on all objects whose value is currently known. \end_layout \begin_layout Standard \family typewriter Matrix specification in the command can be omitted \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Make \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Spinorial Rotation; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset In this case the SL(2,C) matrix \begin_inset Formula $L_A{}^B$ \end_inset must be specified as the value of a special object Spinorial Transformation LS.A'B \family typewriter \series default \shape default (identifier LS \family typewriter \series default \shape default ). \end_layout \begin_layout Standard \family typewriter Command for frame rotation is analogously \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Make Rotation \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Rotation \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Make \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Rotation \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset (( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{00}$ \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{01}$ \end_inset ,...), ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{10}$ \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{11}$ \end_inset ,...),...) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset with the nonsingular \begin_inset Formula $d\times d$ \end_inset rotation matrix \begin_inset Formula \[ A'^a=L^a{}_bA^b,\ \ \mbox{\parm{expr}}_{ab}=L^a{}_b \] \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset verifies that this matrix is a valid \emph on rotation \emph default by checking that frame metric \begin_inset Formula $g_{ab}$ \end_inset \emph on remains unchanged \emph default under this transformation \begin_inset Formula \[ g'_{ab} = L^m{}_a L^n{}_b g_{mn} = g_{ab} \] \end_inset \end_layout \begin_layout Standard \family typewriter Once again the matrix specification can be omitted and transformation \begin_inset Formula $L^a{}_b$ \end_inset can be specified as the value of the object Frame Transformation L'a.b \family typewriter \series default \shape default (identifier L \family typewriter \series default \shape default ) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Make \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Rotation; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Frame rotation commands correctly transform frame and spinor connection 1-forms. \end_layout \begin_layout Standard \family typewriter Finally, there is a special form of the frame transformation command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Change Metric \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Change Metric \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset (( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{00}$ \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{01}$ \end_inset ,...), ( \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{10}$ \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset expr \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula ${}_{11}$ \end_inset ,...),...) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset The only difference between this command and Make Rotation \family typewriter \series default \shape default is that Change Metric \family typewriter \series default \shape default does not impose any restriction on the transformation matrix and transformed metric does not necessary coincides with the original one. \end_layout \begin_layout Standard \family typewriter Sometimes it is convenient to keep some object unchanged under the frame transformation. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Hold \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Hold \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset makes the system to keep the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset unchanged during frame and spinor transformations. The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Release \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Release \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset discards the action of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Hold \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command. \end_layout \begin_layout Subsection \family typewriter Algebraic Classification \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Algebraic classification \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Classify \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Classify \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset performs algebraic classification of the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset object \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset specified by its name or identifier. Currently \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset knows algorithms for classifying the following irreducible spinors \end_layout \begin_layout Standard \family typewriter \begin_inset Tabular <lyxtabular version="3" rows="4" columns="2"> <features rotate="0" tabularvalignment="middle" tabularwidth="0pt"> <column alignment="left" valignment="top"> <column alignment="left" valignment="top"> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $X_{ABCD}$ \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Weyl spinor type \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $X_{AB\dot{C}\dot{D}}$ \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Traceless Ricci spinor type \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $X_{AB}$ \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Electromagnetic stress spinor type \end_layout \end_inset </cell> </row> <row> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter \begin_inset Formula $X_{A\dot{B}}$ \end_inset \end_layout \end_inset </cell> <cell alignment="left" valignment="top" usebox="none"> \begin_inset Text \begin_layout Standard \family typewriter Vector in the spinorial representation \end_layout \end_inset </cell> </row> </lyxtabular> \end_inset \begin_inset Newline newline \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reversemarginpar \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The Classify \family typewriter \series default \shape default command can be applied to any built-in or user-defined object having one of the listed above \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash seethis{ \end_layout \end_inset See page \begin_inset CommandInset ref LatexCommand pageref reference "sumspin" plural "false" caps "false" noprefix "false" \end_inset about summed spinor indices. \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset types of indices. Notice that all spinors must be irreducible (totally symmetric in dotted and undotted indices) and \begin_inset Formula $X_{AB\dot{C}\dot{D}}$ \end_inset , \begin_inset Formula $X_{A\dot{B}}$ \end_inset must be Hermitian. Groups of the irreducible indices must be represented as a single summed index. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash normalmarginpar \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset uses the algorithm by F. \begin_inset space ~ \end_inset W. \begin_inset space ~ \end_inset Letniowski and R. \begin_inset space ~ \end_inset G. \begin_inset space ~ \end_inset McLenaghan [Gen. Rel. Grav. 20 (1988) 463-483] for Petrov-Penrose classification of Weyl spinor \begin_inset Formula $X_{ABCD}$ \end_inset . The obvious simplification of this algorithm is applied to the spinor analog of electromagnetic strength tensor \begin_inset Formula $X_{AB}$ \end_inset . The spinor \begin_inset Formula $X_{AB\dot{C}\dot{D}}$ \end_inset is classified by the algorithm by G. \begin_inset space ~ \end_inset C. \begin_inset space ~ \end_inset Joly, M. \begin_inset space ~ \end_inset A. \begin_inset space ~ \end_inset H. \begin_inset space ~ \end_inset McCallum and W. \begin_inset space ~ \end_inset Seixas [Class. Quantum Grav. 7 (1990) 541-556, Class. Quantum Grav. 8 (1991) 1577-1585]. \end_layout \begin_layout Standard \family typewriter The classification process is accompanied by the tracing messages which can be eliminated by turning \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swinda{ \end_layout \end_inset TRACE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset off the switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset TRACE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . On the contrary if one turns on \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset SHOWEXPR \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset the switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SHOWEXPR \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset prints all expressions which appear during the classification to let you check whether the decision about nonvanishing of these expressions is really correct or not. This facility is important also in classifying \begin_inset Formula $X_{AB\dot{C}\dot{D}}$ \end_inset and \begin_inset Formula $X_{A\dot{B}}$ \end_inset since algebraic type for this objects may depend on the \emph on sign \emph default of some expressions which cannot be determined by \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset correctly. \end_layout \begin_layout Subsection \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset Packages and Functions in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Using \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset packages \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "packages" \end_inset \end_layout \begin_layout Standard \family typewriter Any procedure or function defined in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset package can be used in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset . The package must be loaded either before \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is started or during \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset session by one of the equivalent commands \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Package \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Use Package \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Load \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Use \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset package \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset Newline newline \end_inset Load \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset package \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset where \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset package \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset is the package name. Notice that an identifier must be used for the package name unlike the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset Load \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command described in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash enlargethispage{5mm} \end_layout \end_inset section \begin_inset CommandInset ref LatexCommand ref reference "UnloadLoad" plural "false" caps "false" noprefix "false" \end_inset . Let us consider some examples. The \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset specfn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset contains definitions of various special functions and below we demonstrate 11th Legendre polynomial \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- package specfn; <- LEGENDREP(11,x); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 10 8 6 4 2 x*(88179*x - 230945*x + 218790*x - 90090*x + 15015*x - 693) ——————————————————————- 256 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset Newpage newpage \end_inset \end_layout \begin_layout Standard \family typewriter Another example demonstrates the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset taylor \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset <- Coordinates t, x, y, z; <- www=d(E(x+y)*SIN(x)); <- www; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset x + y x + y (E *(COS(x) + SIN(x))) d x + (E *SIN(x)) d y \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- load taylor; <- TAYLOR(www,x,0,5); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset y y y y y 2 E 4 E 5 6 y y 2 (E + 2*E *x + E *x - —-*x - —-*x + O(x )) d x + (E *x + E *x 6 15 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset y y E 3 E 5 6 + —-*x - —-*x + O(x )) d y 3 30 \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter You can also define your own operators and procedures in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset and later use them in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset . In the following example file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset lasym.red \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset contains a definition of little \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset procedure which computes a leading term of asymptotic expansion of the rational function at large values of some variable. This file is inputted in \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset before \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is started \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{slisting} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 1: in \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset lasym.red \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset procedure leadingterm(w,x); lterm(num(w),x)/lterm(den(w),x); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset leadingterm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset end; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 2: load grg; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset This is GRG 3.2 release 2 (Feb 9, 1997) ... \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset System directory: c: \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset red35 \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset grg32 \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset System variables are upper-cased: E I PI SIN ... Dimension is 4 with Signature (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- Coordinates t, r, theta, phi; <- OMEGA01=(123*r3+2*r+t)/(r+t)5*d theta \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset d phi; <- OMEGA01; \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 3 123*r + 2*r + t (————————————————-) d theta \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d phi 5 4 3 2 2 3 4 5 r + 5*r *t + 10*r *t + 10*r *t + 5*r*t + t \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset <- LEADINGTERM(OMEGA01,r); \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash par \end_layout \end_inset 123 (—–) d theta \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash w \end_layout \end_inset d phi 2 r \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{slisting} \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Anholonomic Basis Mode \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Anholonomic basis mode \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Basis \end_layout \end_inset \begin_inset CommandInset label LatexCommand label name "amode" \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset may work in both holonomic and anholonomic basis modes. In the first default case, values of all expressions are represented in a natural holonomic (coordinate) basis: \begin_inset Formula $d x^\mu,~d x^\mu\wedge x^\nu\dots$ \end_inset for exterior forms and \begin_inset Formula $\partial_\mu=\partial/\partial x^\mu$ \end_inset for vectors. In the second case an arbitrary basis \begin_inset Formula $b^i=b^i_\mu d x^\mu$ \end_inset is used for forms and inverse vector basis \begin_inset Formula $e_i=e_i^\mu\partial_\mu$ \end_inset for vectors ( \begin_inset Formula $b^i_\mu e^\mu_j=\delta^i_j$ \end_inset ). You can specify this basis assigning a value to built-in object Basis \family typewriter \series default \shape default (identifier b \family typewriter \series default \shape default ). If Basis \family typewriter \series default \shape default is not specified by user then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset assumes that it coincides with the frame \begin_inset Formula $b^i=\theta^i$ \end_inset . \end_layout \begin_layout Standard \family typewriter Frame should not be confused with basis. Frame \begin_inset Formula $\theta^a$ \end_inset is used only for \begin_inset Quotes eld \end_inset external \begin_inset Quotes erd \end_inset purposes to represent tensor indices while basis \begin_inset Formula $b^i$ \end_inset and vector basis \begin_inset Formula $e_i$ \end_inset is used for \begin_inset Quotes eld \end_inset internal \begin_inset Quotes erd \end_inset purposes to represent form and vector valued object components. \end_layout \begin_layout Standard \family typewriter The command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Anholonomic \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Anholonomic; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset switches the system to the anholonomic basis mode and the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Holonomic \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset Holonomic; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset switches it back to the standard holonomic mode. \end_layout \begin_layout Standard \family typewriter Working in anholonomic mode \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset creates some internal tables for efficient calculation of exterior differentiation and complex conjugation. In anholonomic mode the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Unload \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Unload All > \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter automatically saves these tables into the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . Subsequent \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Load \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Load \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset file \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout " \end_layout \end_inset ; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter restores the tables and automatically switches the current mode to anholonomic one. Note that automatic anholonomic mode saving/restoring works only if All \family typewriter \series default \shape default is used in Unload \family typewriter \series default \shape default command. \end_layout \begin_layout Standard \family typewriter One can find out the current mode with the help of the command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Show Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cmdind{ \end_layout \end_inset Status \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash command{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash opt{ \end_layout \end_inset Show \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset Status; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Subsection \family typewriter Synonymy \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Synonymy \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Sometimes \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset commands may be rather long. For instance, in order to find the curvature 2-form \begin_inset Formula $\Omega_{ab}$ \end_inset from the spinorial curvature \begin_inset Formula $\Omega_{AB}$ \end_inset and \begin_inset Formula $\Omega_{\dot{A}\dot{B}}$ \end_inset the following command should be used \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find Curvature From Spinorial Curvature; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Certainly, this command is clear but typing of such long phrases may be very dull. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset has synonymy mechanism which allows one to make input much shorter. \end_layout \begin_layout Standard \family typewriter The synonymous words in commands and object names are considered to be equivalent. The complete list of predefined \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset synonymy is given in appendix D. Here we present just the most important ones \end_layout \begin_layout Verbatim Connection Con \end_layout \begin_layout Verbatim Constants Const Constant \end_layout \begin_layout Verbatim Coordinates Cord \end_layout \begin_layout Verbatim Curvature Cur \end_layout \begin_layout Verbatim Dotted Do \end_layout \begin_layout Verbatim Equation Equations Eq \end_layout \begin_layout Verbatim Find F Calculate Calc \end_layout \begin_layout Verbatim Functions Fun Function \end_layout \begin_layout Verbatim Next N \end_layout \begin_layout Verbatim Show ? \end_layout \begin_layout Verbatim Spinor Spin Spinorial Sp \end_layout \begin_layout Verbatim Switch Sw \end_layout \begin_layout Verbatim Symmetries Sym Symmetric \end_layout \begin_layout Verbatim Undotted Un \end_layout \begin_layout Verbatim Write W \end_layout \begin_layout Standard \family typewriter Words in each line are considered as equivalent in all commands. Thus the above command can be abbreviated as \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter F cur from sp cur; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Section \begin_inset CommandInset ref LatexCommand ref reference "tuning" plural "false" caps "false" noprefix "false" \end_inset explains how to change built-in synonymy and how to define a new one. \end_layout \begin_layout Subsection \family typewriter Compound Commands \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout Compound commands \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Sometime one may need to perform several consecutive actions with one object. In this case we can use so called \emph on compound commands \emph default to shorten the input. Internally \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset replaces each compound command by several usual ones. For example the compound command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find and Write Einstein Equation; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter to a pair of usual ones \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find Einstein Equation; Write Einstein Equation; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Actions (commands) can be attached to the end of the compound command as well: \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find, Write Curvature and Erase It; \begin_inset space \qquad{} \end_inset \begin_inset space \qquad{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash udr \end_layout \end_inset Find & Write & Erase Curvature; \begin_inset space \qquad{} \end_inset \begin_inset space \qquad{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash udr \end_layout \end_inset Find Curvature; Write Curvature; Erase Curvature; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Note that we have used , \family typewriter \series default \shape default and & \family typewriter \series default \shape default instead of and \family typewriter \series default \shape default in this example. All these separators are equivalent in compound commands. \end_layout \begin_layout Standard \family typewriter Now let us consider the case when one needs to perform a single action with several objects. The command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Write Frame, Vector Frame and Metric; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter is equivalent to \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Write Frame; Write Vector Frame; Write Metric; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Way specification can be attached to the Find \family typewriter \series default \shape default command: \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find QT, QP From Torsion using spinors; \begin_inset space \qquad{} \end_inset \begin_inset space \qquad{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash udr \end_layout \end_inset Find QT From Torsion using spinors; Find QP From Torsion using spinors; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter One can combine several actions and several objects. For example, the command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find omega, Curvature by Standard Way and Write and Erase Them; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter is equivalent to the sequence of \begin_inset Formula $(2{\rm\ objects})\times(3{\rm\ commands}) =6$ \end_inset commands \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Find omega by Standard Way; Find Curvature by Standard Way; Write omega; Write Curvature; Erase omega; Erase Curvature; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter Note that the way specification is attached only to \begin_inset Quotes eld \end_inset left \begin_inset Quotes erd \end_inset commands (Find \family typewriter \series default \shape default in our case). \end_layout \begin_layout Standard \family typewriter The compound commands mechanism works only with Find \family typewriter \series default \shape default , Erase \family typewriter \series default \shape default , Write \family typewriter \series default \shape default and Evaluate \family typewriter \series default \shape default commands. \end_layout \begin_layout Standard \family typewriter And finally, \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset always replaces Re- \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \family typewriter \series default \shape default by Erase and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash parm{ \end_layout \end_inset command \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ; \family typewriter \series default \shape default . For example \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter Re-Calculate Maxwell Equations; \begin_inset space \qquad{} \end_inset \begin_inset space \qquad{} \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash udr \end_layout \end_inset Erase and Calculate Maxwell Equations; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter You can see how \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset expand compound commands into the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash swind{ \end_layout \end_inset SHOWCOMMANDS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset usual ones by turning switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset SHOWCOMMANDS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset on. \end_layout \begin_layout Section \family typewriter Tuning \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset CommandInset label LatexCommand label name "tuning" \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset can be tuned according to your needs and preferences. The configuration files allow one to change some default settings and the environment variable \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset grg \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines the system directory which can be used as the depository for frequently used files. \end_layout \begin_layout Subsection \family typewriter Configuration Files \end_layout \begin_layout Standard \family typewriter \begin_inset CommandInset label LatexCommand label name "configsect" \end_inset \end_layout \begin_layout Standard \family typewriter The configuration files allows one to establish \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash begin{list} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset Formula $\bullet$ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash labelwidth \end_layout \end_inset =8mm \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash leftmargin \end_layout \end_inset =10mm \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Default dimension and signature. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Initial position of switches. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset packages which must be preloaded. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Synonymy. \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash item \end_layout \end_inset Default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset start up method. \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash end{list} \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter There are two configuration files. First \emph on global \emph default configuration file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grgcfg.sl \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines the settings \begin_inset Index idx status collapsed \begin_layout Plain Layout Global configuration file \end_layout \end_inset during system installation when \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is compiled. These global settings become permanent and can be changed only if \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is recompiled. The \emph on local \emph default configuration file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grg.cfg \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset allows one to override global settings locally. \begin_inset Index idx status collapsed \begin_layout Plain Layout Local configuration file \end_layout \end_inset When \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset starts it search the file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grg.cfg \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset in current directory (folder) and if it is present uses the corresponding settings. \end_layout \begin_layout Standard \family typewriter Below we are going to explain how to change settings in both global and local configuration files but before doing this we must emphasize that this need some care. First, the configuration files use LISP command format which differs from usual \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset commands. Second, is something is wrong with configuration file then no clear diagnostic is provided. Finally, if global configuration is damaged you will not be able to compile \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset . The best strategy is to make a back-up copy of the configuration files before start editing them. Notice that lines preceded by the percent sign \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset % \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset are ignored by the system (comments). \end_layout \begin_layout Standard \family typewriter Both local \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grg.cfg \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and global \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grgcfg.sl \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset configuration files have similar structure and can include the following commands. \end_layout \begin_layout Standard \family typewriter Command \begin_inset Index idx status collapsed \begin_layout Plain Layout Signature!default \end_layout \end_inset \begin_inset Index idx status collapsed \begin_layout Plain Layout Dimension!default \end_layout \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter (signature!> - + + + +) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter establishes default dimension 5 with the signature \begin_inset Formula $\scriptstyle(-,+,+,+,+)$ \end_inset . Do not forget \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ! \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and spaces between \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset + \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset and \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset - \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . This command \emph on must be present \emph default in the global configuration file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grgcfg.sl \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset otherwise \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset cannot be compiled. \end_layout \begin_layout Standard \family typewriter The commands \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter (on!> page) (off!> allfac) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter change default switch position. In this example we turn on the switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset PAGE \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (this switch is defined in DOS \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset only and allows one to scroll back and forth through input and output) and turn off switch \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset ALLFAC \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . \end_layout \begin_layout Standard \family typewriter The command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter (package!> taylor) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter makes the system to load \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset package \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset taylor \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset during \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset start. \end_layout \begin_layout Standard \family typewriter The command of the form \begin_inset Index idx status collapsed \begin_layout Plain Layout Synonymy \end_layout \end_inset \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter (synonymous!> ( affine aff ) ( antisymmetric asy ) ( components comp ) ( unload save ) ) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter defines synonymous words. The words in each line will be equivalent in all \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset commands. \end_layout \begin_layout Standard \family typewriter Finally the command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter (setq ![autostart!] nil) \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter alters default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset start up method. It makes sense only in the global configuration file \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash file{ \end_layout \end_inset grgcfg.sl \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset . By default \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset is launched by single command \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter load grg; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter which firstly load the program into memory and then automatically starts it. Unfortunately on some systems this short method does not work properly: \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset shows wrong timing during computations, the \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset quit; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset command returns the control to \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash reduce \end_layout \end_inset \begin_inset space \space{} \end_inset session instead of terminating the whole program. If the aforementioned option is activated then \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset must be launched by two commands \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter load grg; grg; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter which fixes the problems. Here first command just loads the program into memory and second one starts it manually. Notice that one can always use commands \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter load grg32; grg; \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter to start \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset manually. Command \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset load grg32; \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset always loads \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset into memory without starting it independently on the option under consideration. \end_layout \begin_layout Subsection \family typewriter System Directory \end_layout \begin_layout Standard \family typewriter \begin_inset Index idx status collapsed \begin_layout Plain Layout System directory \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter The environment variable \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset grg \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset or \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset GRG \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset defines so called \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash grg \end_layout \end_inset \begin_inset space \space{} \end_inset system directory (folder). The way of setting this variable is operating system dependent. For example the following commands can be used to set \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash comm{ \end_layout \end_inset grg \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset variable in DOS, UNIX and VAX/VMS respectively: \begin_inset listings lstparams "float" inline false status collapsed \begin_layout Plain Layout \begin_inset Caption Standard \begin_layout Standard \family typewriter set grg=d: \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset xxx \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset yyy \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash bs \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset DOS \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset setenv grg /xxx/yyy/ \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset UNIX \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset define grg SYS \begin_inset Formula $USER:[xxx.yyy] {\rm VAX/VMS} {listing} The value of the variable \comm{grg} must point out to some directory. In DOS and UNIX the directory name must include trailing \comm{\bs} or \comm{/} respectively. The command\cmdind{Show Status}\cmdind{Status} \command{\opt{Show} Status;} prints current system directory. When \grg\ tries to input some batch file containing \grg\ commands it first searches it in the current working directory and if the file is absent then it tries to find it in the system directory. Therefore if you have some frequently used files you can define the system directory and move these files there. In this case it is not necessary to keep them in each working directory. Notice \grg\ uses the same strategy when opening local configuration file \file{grg.cfg}. Thus if system directory is defined and it contains the file \file{grg.cfg} the settings contained in this file effectively overrides global settings without recompiling \grg. \section{Examples} In this section we want to demonstrate how \grg\ can be applied to solve simple but realistic problem. We want to calculate the Ricci tensor for the Robertson-Walker metric by three different methods. First \grg\ task (program) \begin{listing} Coordinates t,r,theta,phi; Function a(t); Frame T0=d t, T1=a*d r, T2=a*r*d theta, T3=a*r*SIN(theta)*d phi; ds2; Find and Write Ricci Tensor; RIC(\_j,\_k); \end{listing} defines the Robertson-Walker metric using the tetrad formalism with the orthonormal Lorentzian tetrad $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash theta \end_layout \end_inset a \begin_inset Formula $. Using built-in formulas for the Ricci tensor the only one command is required to accomplish out goal {\tt Find and Write Ricci Tensor;}. The command {\tt ds2;} just shows the metric we are dealing with. Notice that command {\tt Find ...} gives the \emph{tetrad} components of the Ricci tensor $ \end_inset R \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. Thus, in addition we print coordinate components of the tensor $ \end_inset R \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mu \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash nu \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ by the command {\tt RIC(\_j,\_k);}. The hard-copy of the corresponding \grg\ session is presented below \enlargethispage{4mm} \begin{slisting} <- Coordinates t, r, theta, phi; <- Function a(t); <- Frame T0=d t, T1=a*d r, T2=a*r*d theta, T3=a*r*SIN(theta)*d phi; <- ds2; Assuming Default Metric. Metric calculated By default. 0.16 sec 2 2 2 2 2 2 2 2 2 2 2 ds = - d t + (a ) d r + (a *r ) d theta + (SIN(theta) *a *r ) d phi <- Find and Write Ricci Tensor; Sqrt det of metric calculated. 0.21 sec Volume calculated. 0.21 sec Vector frame calculated From frame. 0.21 sec Inverse metric calculated From metric. 0.21 sec Frame connection calculated. 0.38 sec Curvature calculated. 0.49 sec Ricci tensor calculated From curvature. 0.54 sec Ricci tensor: - 3*DF(a,t,2) RIC = ---------------- 00 a \newpage 2 DF(a,t,2)*a + 2*DF(a,t) RIC = -------------------------- 11 2 a 2 DF(a,t,2)*a + 2*DF(a,t) RIC = -------------------------- 22 2 a 2 DF(a,t,2)*a + 2*DF(a,t) RIC = -------------------------- 33 2 a <- RIC(_j,_k); - 3*DF(a,t,2) j=0 k=0 : ---------------- a 2 j=1 k=1 : DF(a,t,2)*a + 2*DF(a,t) 2 2 j=2 k=2 : r *(DF(a,t,2)*a + 2*DF(a,t) ) 2 2 2 j=3 k=3 : SIN(theta) *r *(DF(a,t,2)*a + 2*DF(a,t) ) \end{slisting} Tracing messages demonstrate that \grg\ automatically applied several built-in equations to obtain required value of $ \end_inset R \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The metric is automatically assumed to be Lorentzian $ \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset diag \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (-1,1,1,1) \begin_inset Formula $. First \grg\ computed the frame connection 1-form $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $. Next the curvature 2-form $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ was computed using standard equation (\ref{omes}) on page \pageref{omes}. Finally the Ricci tensor was obtained using relation (\ref{rics}) on page \pageref{rics}. Second \grg\ task is similar to the first one: \begin{listing} Coordinates t,r,theta,phi; Function a(t); Metric G00=-1, G11=a^2, G22=(a*r)^2, G33=(a*r*SIN(theta))^2; ds2; Find and Write Ricci Tensor; \end{listing} The only difference is that now we work in the coordinate formalism by assigning value to the metric rather than frame. The frame is assumed to be holonomic automatically. \begin{slisting} <- Coordinates t, r, theta, phi; <- Function a(t); <- Metric G00=-1, G11=a^2, G22=(a*r)^2, G33=(a*r*SIN(theta))^2; <- ds2; Assuming Default Holonomic Frame. Frame calculated By default. 0.11 sec 2 2 2 2 2 2 2 2 2 2 2 ds = - d t + (a ) d r + (a *r ) d theta + (SIN(theta) *a *r ) d phi <- Find and Write Ricci Tensor; Sqrt det of metric calculated. 0.22 sec Volume calculated. 0.22 sec Vector frame calculated From frame. 0.22 sec Inverse metric calculated From metric. 0.27 sec Frame connection calculated. 0.33 sec Curvature calculated. 0.60 sec Ricci tensor calculated From curvature. 0.60 sec Ricci tensor: - 3*DF(a,t,2) RIC = ---------------- t t a 2 RIC = DF(a,t,2)*a + 2*DF(a,t) r r 2 2 RIC = r *(DF(a,t,2)*a + 2*DF(a,t) ) theta theta 2 2 2 RIC = SIN(theta) *r *(DF(a,t,2)*a + 2*DF(a,t) ) phi phi \end{slisting} Once again \grg\ uses the same built-in formulas to compute the Ricci tensor but now all quantities have holonomic indices instead of tetrad ones. Finally the third task demonstrate how \grg\ can be used without built-in equations. Once again we use coordinate formalism and declare two new objects the Christoffel symbols \comm{Chr} and Ricci tensor \comm{Ric} (since \grg\ is case sensitive they are different from the built-in objects \comm{CHR} and \comm{RIC}). Next we use well-known equations to compute these quantities \begin{listing} Coordinates t,r,theta,phi; Function a(t); Metric G00=-1, G11=a^2, G22=(a*r)^2, G33=(a*r*SIN(theta))^2; ds2; New Chr^a_b_c with s(2,3); Chr(j,k,l)= 1/2*GI(j,m)*(@x(k)|G(l,m)+@x(l)|G(k,m)-@x(m)|G(k,l)); New Ric_a_b with s(1,2); Ric(j,k) = @x(n)|Chr(n,j,k) - @x(k)|Chr(n,j,n) + Chr(n,m,n)*Chr(m,j,k) - Chr(n,m,k)*Chr(m,n,j); Write Ric; \end{listing} The hard-copy of the corresponding session is \begin{slisting} <- Coordinates t, r, theta, phi; <- Function a(t); <- Metric G00=-1, G11=a^2, G22=(a*r)^2, G33=(a*r*SIN(theta))^2; <- ds2; Assuming Default Holonomic Frame. Frame calculated By default. 0.16 sec 2 2 2 2 2 2 2 2 2 2 2 ds = - d t + (a ) d r + (a *r ) d theta + (SIN(theta) *a *r ) d phi <- New Chr^a_b_c with s(2,3); <- Chr(j,k,l)=1/2*GI(j,m)*(@x(k)|G(l,m)+@x(l)|G(k,m)-@x(m)|G(k,l)); Inverse metric calculated From metric. 0.27 sec <- New Ric_a_b with s(1,2); <- Ric(j,k)=@x(n)|Chr(n,j,k)-@x(k)|Chr(n,j,n)+Chr(n,m,n)*Chr(m,j,k) -Chr(n,m,k)*Chr(m,n,j); <- Write Ric; The Ric: - 3*DF(a,t,2) Ric = ---------------- t t a 2 Ric = DF(a,t,2)*a + 2*DF(a,t) r r \newpage 2 2 Ric = r *(DF(a,t,2)*a + 2*DF(a,t) ) theta theta 2 2 2 Ric = SIN(theta) *r *(DF(a,t,2)*a + 2*DF(a,t) ) phi phi \end{slisting} \chapter{Formulas} \parindent=0pt \arraycolsep=1pt \parskip=1.6mm plus 1mm minus 1mm This chapter describes in usual mathematical manner all \grg\ built-in objects and formulas. The description is extremely short since it is intended for reference only. If not stated explicitly we use lower case greek letters $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash alpha \end_layout \end_inset , \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash beta \end_layout \end_inset ,… \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ for holonomic (coordinate) indices; $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset a,b,c,d,m,n \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ for anholonomic frame indices and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset i,j,k,l \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ for enumerating indices. To establish the relationship between \grg\ built-in object6s and mathematical quantities we use the following notation \[\mbox{\tt Frame Connection omega'a.b} = \omega^a{}_b \] This equality means that there is built-in object named {\tt Frame Connection} having identifier {\tt omega} which represent the frame connection 1-form $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $. If the name is omitted then we deal with \emph{macro} object (see page \pageref{macro}). The notation for indices in the left-hand side of such equalities is the same as in the {\tt New object} declaration and is explained on page \pageref{indices}. This chapter contains not only definitions of all built-in objects but all formulas which \grg\ knows and can apply to find their value. If an object has several formulas for its computation when each formula is given together with the corresponding name which is printed in the typewriter font. In the case then an object has only one associated formula the way name is usually omitted. \section{Dimension and Signature} Let us denote the space-time dimensionality by $ \end_inset d \begin_inset Formula $ and $ \end_inset n \begin_inset Formula $'th element of the signature specification $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset diag \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+1,-1,…) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ by $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset diag \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset n \begin_inset Formula $ ($ \end_inset n \begin_inset Formula $ runs from 0 to $ \end_inset d-1 \begin_inset Formula $). There are several macro objects which gives access to the dimension and signature \object{dim}{d} \object{sdiag.idim}{{\rm diag}_i} \object{sgnt \mbox{=} sign}{s=\prod^{d-1}_{i=0}{\rm diag}_i} \object{mpsgn}{{\rm diag}_0} \object{pmsgn}{-{\rm diag}_0} The macros (two equivalent ones) which give access to coordinates \object{X\^m \mbox{=} x\^m}{x^\mu} \section{Metric, Frame and Basis} Frame $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash theta \end_layout \end_inset a \begin_inset Formula $ and metric $ \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ plays the fundamental role in \grg. Together they determine the space-time line element \begin{equation} ds^2 = g_{ab}\,\theta^a\!\otimes\theta^b = g_{\mu\nu}\,dx^\mu\!\otimes dx^\nu \end{equation} The corresponding objects are \object{Frame T'a}{\theta^a=h^a_\mu dx^\mu} \object{Metric G.a.b}{g_{ab}} and ``inverse'' objects are \object{Vector Frame D.a}{\partial_a=h^\mu_a\partial_\mu} \object{Inverse Metric GI'a'b}{g^{ab}} The frame can be computed by two ways. First, {\tt By default} frame is assumed to be holonomic \begin{equation} \theta^a = dx^\alpha \end{equation} and {\tt From vector frame} \begin{equation} \theta^a= |h_a^\mu|^{-1} d x^\mu \end{equation} The vector frame can be obtained {\tt From frame} \begin{equation} \partial_a= |h^a_\mu|^{-1} \partial_\mu \end{equation} The metric can be computed {\tt By default} \index{Metric!default value} \begin{equation} g_{ab} = {\rm if}\ a=b\ {\rm then}\ {\rm diag}_a\ {\rm else}\ 0 \end{equation} or {\tt From inverse metric} \begin{equation} g_{ab} = |g^{ab}|^{-1} \end{equation} The inverse metric can be computed {\tt From metric} \begin{equation} g^{ab} = |g_{ab}|^{-1} \end{equation} The holonomic metric $ \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mu \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash nu \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and frame $ \end_inset ha \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mu \end_layout \end_inset \begin_inset Formula $ are given by the macro objects: \object{g\_m\_n}{g_{\mu\nu}} \object{gi\^m\^n}{g^{\mu\nu}} \object{h'a\_m}{h^a_\mu} \object{hi.a\^m}{h_a^\mu} The metric determinants and related densities \object{Det of Metric detG}{g={\rm det}|g_{ab}|} \object{Det of Holonomic Metric detg}{{\rm det}|g_{\mu\nu}|} \object{Sqrt Det of Metric sdetG}{\sqrt{sg}} The volume $ \end_inset d \begin_inset Formula $-form \object{Volume VOL}{\upsilon = \sqrt{sg}\,\theta^0\wedge\dots\wedge\,\theta^{d-1} =\frac{1}{d!}{\cal E}_{a_0\dots a_{d-1}}\,\theta^{a_0}\wedge\dots\wedge\,\theta^{a_{d-1}}} The so called s-forms play the role of basis in the space of the 2-forms \object{S-forms S'a'b}{S^{ab}=\theta^a\wedge\theta^b} The basis and corresponding inverse vector basis are used when \grg\ works in the anholonomic mode \seethis{See page \pageref{amode}.} \object{Basis b'idim }{b^i=b^i_\mu dx^\mu} \object{Vector Basis e.idim }{e_i=b_i^\mu\partial_\mu} The basis can be computed {\tt From frame} \begin{equation} b^i=\theta^i \end{equation} or {\tt From vector basis} \begin{equation} b^i = |b_i^\mu|^{-1}dx^\mu \end{equation} The vector basis can be computed {\tt From basis} \begin{equation} e_i = |b^i_\mu|^{-1}\partial_\mu \end{equation} \section{Delta and Epsilon Symbols} Macro objects for Kronecker delta symbols \object{del\^m\_n}{\delta^\mu_\nu} \object{delh'a.b}{\delta^a_b} and totally antisymmetric tensors \object{eps.a.b.c.d}{{\cal E}_{abcd},\quad{\cal E}_{0123}=\sqrt{sg}} \object{epsi'a'b'c'd}{{\cal E}^{abcd},\quad{\cal E}_{0123}=\frac{s}{\sqrt{sg}}} \object{epsh\_m\_n\_k\_l}{{\cal E}_{\mu\nu\kappa\lambda},\quad{\cal E}_{0123}=\sqrt{s\,{\rm det}|g_{\mu\nu}|}} \object{epsih\^m\^n\^k\^l}{{\cal E}^{\mu\nu\kappa\lambda},\quad{\cal E}_{0123}=\frac{s}{\sqrt{s\,{\rm det}|g_{\mu\nu}|}}} The definition for epsilon-tensors is given for dimension 4. The generalization to other dimensions is obvious. \section{Dualization} We use the following definition for the dualization operation. For any $ \end_inset p \begin_inset Formula $-form \begin{equation} \omega_p=\frac{1}{p!}\omega_{\alpha_1\dots\alpha_p}dx^{\alpha_1}\wedge \dots\wedge dx^{\alpha_p} \end{equation} the dual $ \end_inset (d-p) \begin_inset Formula $-form is \begin{equation} *\omega_p=\frac{1}{p!(d-p)!}{\cal E}_{\alpha_1\dots\alpha_{d-p}} {}^{\beta_1\dots\beta_p}\,\omega_{\beta_1\dots\beta_p}\, dx^{\alpha_1}\wedge\dots\wedge dx^{\alpha_{d-p}} \end{equation} The equivalent relation which also uniquely defines the $ \end_inset * \begin_inset Formula $ operation is \begin{equation} *(\theta^{a_1}\wedge\dots\wedge \theta^{a_p}) = (-1)^{p(d-p)} \partial_{a_p}\ipr\dots\partial_{a_1}\ipr\,\upsilon \end{equation} With such convention we have the following identities \begin{eqnarray} **\omega_p &=& s(-1)^{p(d-p)}\,\omega_p \\[0.5mm] *\upsilon &=& s \\[0.5mm] *1 &=& \upsilon \end{eqnarray} \section{Spinors} \label{spinors1} The notion of spinors in \grg\ is restricted to 4-dimensional spaces of Lorentzian signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ or $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ only. In this section the upper sign relates to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and lower one to $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. In addition to work with spinors the metric must have the following form which we call the \emph{standard null metric} \index{Metric!Standard Null} \index{Standard null metric}\index{Spinors}\index{Spinors!Standard null metric} \begin{equation} g_{ab}=g^{ab}=\pm\left(\begin{array}{rrrr} 0 & -1 & 0 & 0 \\ -1 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1 \\ 0 & 0 & 1 & 0 \end{array}\right) \end{equation} Such value of the metric can be established by the command \cmdind{Null Metric} {\tt Null metric;}. Therefore the line-element for spinorial formalism has the form \begin{equation} ds^2 = \pm(-\theta^0\!\otimes\theta^1 -\theta^1\!\otimes\theta^0 +\theta^2\!\otimes\theta^3 +\theta^3\!\otimes\theta^2) \end{equation} We require also the conjugation rules for this null tetrad (frame) be \begin{equation} \overline{\theta^0}=\theta^0,\quad \overline{\theta^1}=\theta^1,\quad \overline{\theta^2}=\theta^3,\quad \overline{\theta^3}=\theta^2 \end{equation} For such a metric and frame we fix sigma-matrices in the following form \index{Sigma matrices} \begin{eqnarray} \label{sigma} &&\sigma_0{}^{1\dot{1}}= \sigma_1{}^{0\dot{0}}= \sigma_2{}^{1\dot{0}}= \sigma_3{}^{0\dot{1}}=1 \\[1mm] && \sigma^0{}_{1\dot{1}}= \sigma^1{}_{0\dot{0}}= \sigma^2{}_{1\dot{0}}= \sigma^3{}_{0\dot{1}}=\mp1 \end{eqnarray} The sigma-matrices obey the rules \begin{eqnarray} g_{mn}\sigma^m\!{}_{A\dot B}\sigma^n\!{}_{C\dot D} &=& \mp \epsilon_{AC}\epsilon_{\dot B\dot D} \\[1mm] \sigma^{aM\dot N}\sigma^b\!{}_{M\dot N} &=& \mp g^{ab} \end{eqnarray} The antisymmetric SL(2,C) spinor metric \begin{equation} \epsilon_{AB}=\epsilon^{AB} =\epsilon_{\dot A\dot B} =\epsilon^{\dot A\dot B}= \left(\begin{array}{rr} 0 & 1 \\ -1 & 0 \end{array}\right) \end{equation} can be used to raise and lower spinor indices \begin{equation} \varphi^A=\varphi_B\,\epsilon^{BA},\qquad \varphi_A=\epsilon_{AB}\,\varphi^B \end{equation} The following macro objects represent standard spinorial quantities \object{DEL'A.B}{\delta^A_B} \object{EPS.A.B}{\epsilon_{AB}} \object{EPSI'A'B}{\epsilon^{AB}} \object{sigma'a.A.B\cc}{\sigma^a\!{}_{A\dot B}} \object{sigmai.a'A'B\cc}{\sigma_a{}^{A\dot B}} The relationship between tensors and spinors is established by the sigma-matrices \begin{eqnarray} X^a &\tsst& X^{A\dot A}=A^a\sigma_a{}^{A\dot A} \\ X_a &\tsst& X_{A\dot A}=A_a\sigma^a\!{}_{A\dot A} \end{eqnarray} where sigma-matrices are given by Eq. (\ref{sigma}) We shall denote similar equations by the sign $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash tsst \end_layout \end_inset \begin_inset Formula $ conserving alphabetical relationship between tensor indices in the left-hand side and spinorial one in the right-hand side: $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash tsst \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset b \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash tsst \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset Formula $. There is one quite important special case. Any real antisymmetric tensor $ \end_inset X \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ are equivalent to the pair of conjugated irreducible (symmetric) spinors \begin{eqnarray} && X_{ab}=X_{[ab]} \tsst X_{A\dot AB\dot B}= \epsilon_{AB} X_{\dot A\dot B} + \epsilon_{\dot A\dot B}X_{AB} \nonumber\\[1mm] && X_{AB}=\frac{1}{2}X_{A\dot AB\dot B}\epsilon^{\dot A\dot B},\ X_{\dot A\dot B}=\frac{1}{2}X_{A\dot AB\dot B}\epsilon^{AB} \end{eqnarray} The explicit form of these relations for the sigma-matrices (\ref{sigma}) is \begin{equation} \begin{array}{rclrcl} X_0 &=& X_{13} & X_{\dot0} &=& X_{12} \\[1mm] X_1 &=&-\frac{1}{2}(X_{01}-X_{23})\qquad & X_{\dot1} &=& -\frac{1}{2}(X_{01}+X_{23}) \\[1mm] X_2 &=& -X_{02} & X_{\dot2} &=& -X_{03} \end{array}\label{asys} \end{equation} and the ``inverse'' relation \begin{equation} \begin{array}{rclrcl} X_{01} &=& -X_1-X_{\dot1},\qquad & X_{23} &=& X_1-X_{\dot1}, \\[1mm] X_{02} &=& -X_2, & X_{12} &=& X_{\dot0}, \\[1mm] X_{03} &=& -X_{\dot 2}, & X_{13} &=& X_0 \end{array}\label{asyt} \end{equation} We shall apply the relations (\ref{asys}) and (\ref{asyt}) to various antisymmetric quantities. In particular the {\tt Spinorial S-forms} \object{Undotted S-forms SU.AB}{S_{AB}} \object{Dotted S-forms SD.AB\cc}{S_{\dot A\dot B}} The {\tt Standard way} to compute these quantities uses relations (\ref{asys}) \begin{equation} S_{ab}=\theta_a\wedge\theta_b \tsst \epsilon_{AB} S_{\dot A\dot B} + \epsilon_{\dot A\dot B}S_{AB} \end{equation} Spinorial S-forms are self dual \begin{equation} *S_{AB}=iS_{AB},\qquad *S_{\dot A\dot B}=-iS_{\dot A\dot B} \end{equation} and exteriorly orthogonal \begin{equation} S_{AB}\wedge S_{CD}=-\frac{i}2\upsilon(\epsilon_{AC}\epsilon_{BD}+ \epsilon_{AD}\epsilon_{BC}),\quad S_{AB}\wedge S_{\dot C\dot D}=0 \end{equation} There is one subtle pint concerning tensor quantities in the spinorial formalism. Since spinorial null tetrad is complex with the conjugation rule $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash overline \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash theta \end_layout \end_inset 2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash theta \end_layout \end_inset 3 \begin_inset Formula $ all tensor quantities represented in this frame also becomes complex with similar conjugation rules for any tensor index. There is special macro object {\tt cci} which performs such ``index conjugation'': {\tt cci{0}=0}, {\tt cci(1)=1}, {\tt cci{2}=3}, {\tt cci(3)=2}. Therefore the correct expression for the $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash overline \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash theta \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is {\tt \cc T(cci(a))} but not {\tt \cc T(a)}. \section{Connection, Torsion and Nonmetricity} \label{conn1} Covariant derivatives and differentials for quantities having frame and coordinate indices are \begin{eqnarray} DX^a{}_b &=& dX^a{}_b + \omega^a{}_m\wedge X^m{}_b - \omega^m{}_b\wedge X^a{}_m \\[1mm] DX^\mu{}_\nu &=& dX^\mu{}_\nu + \Gamma^\mu{}_\pi\wedge X^\pi{}_\nu - \Gamma^\pi{}_\nu\wedge X^\mu{}_\pi \end{eqnarray} The corresponding built-in connection 1-forms are \object{Frame Connection omega'a.b}{\omega^a{}_b=\omega^a{}_{b\mu}dx^\mu} \object{Holonomic Connection GAMMA\^m\_n} {\Gamma^\mu{}_\nu=\Gamma^\mu{}_{\nu\pi}dx^\pi} Frame connection can be computed {\tt From holonomic connection} \begin{equation} \omega^a{}_b = \Gamma^a{}_b + dh^\mu_b\,h^a_\mu \end{equation} and inversely holonomic connection can be obtained {\tt From frame connection} \begin{equation} \Gamma^\mu{}_\nu=\omega^\mu{}_\nu + dh^b_\nu\,h^\mu_b \end{equation} By default these connections are Riemannian (i.e. symmetric and metric compatible). To work with nonsymmetric connection with torsion the switch \comm{TORSION}\swinda{TORSION} must be turned on. Then the torsion 2-form is \object{Torsion THETA'a}{\Theta^a=\frac12Q^a{}_{pq}S^{pq},\quad Q^a{}_{bc}=\Gamma^a{}_{bc}-\Gamma^a_{cb}} Finally to work with non metric-compatible spaces with nonmetricity the switch \comm{NONMETR}\swinda{NONMETR} must be turned on. The nonmetricity 1-form is \object{Nonmetricity N.a.b}{N_{ab}=N_{ab\mu}dx^\mu, \quad N_{ab\mu}=-\nabla_\mu g_{ab}} In general any torsion or nonmetricity related object is defined iff the corresponding switch is on. If either \comm{TORSION} or \comm{NONMETR} is on then Riemannian versions of the connection 1-forms are available as well \object{Riemann Frame Connection romega'a.b} {\rim{\omega}{}^a{}_b} \object{Riemann Holonomic Connection RGAMMA\^m\_n} {\rim{\Gamma}{}^\mu{}_\nu} The Riemann holonomic connection can be obtained {\tt From Riemann frame connection} \begin{equation} \rim{\Gamma}{}^\mu{}_\nu=\rim{\omega}{}^\mu{}_\nu + dh^b_\nu\,h^\mu_b \end{equation} If torsion is nonzero but nonmetricity vanishes (\comm{TORSION} is on, \comm{NONMETR} is off) then the difference between the connection and Riemann connection is called the contorsion 1-form \object{Contorsion KQ'a.b}{\stackrel{\scriptscriptstyle Q}{K}\!{}^a{}_b= \stackrel{\scriptscriptstyle Q}{K}\!{}^a{}_{b\mu}dx^\mu= \Gamma^a{}_b-\rim{\Gamma}{}^a{}_b} If nonmetricity is nonzero but torsion vanishes (\comm{TORSION} is off, \comm{NONMETR} is on) then the difference between the connection and Riemann connection is called the nonmetricity defect \object{Nonmetricity Defect KN'a.b} {\stackrel{\scriptscriptstyle N}{K}\!{}^a{}_b= \stackrel{\scriptscriptstyle N}{K}\!{}^a{}_{b\mu}dx^\mu= \Gamma^a{}_b-\rim{\Gamma}{}^a{}_b} Finally if both torsion and nonmetricity are nonzero (\comm{TORSION} and \comm{NONMETR} are on) then we \object{Connection Defect K'a.b} {K^a{}_b=K^a{}_{b\mu}dx^\mu= \Gamma^a{}_b-\rim{\Gamma}{}^a{}_b} \begin{equation} K^a{}_b = \stackrel{\scriptscriptstyle Q}{K}\!{}^a{}_b + \stackrel{\scriptscriptstyle N}{K}\!{}^a{}_b \end{equation} For the sake of convenience we introduce also macro objects which compute the usual Christoffel symbols \object{CHR\^m\_n\_p }{ \{{}^\mu_{\nu\pi}\} = \frac{1}{2}g^{\mu\tau}(\partial_\pi g_{\nu\tau} +\partial_\nu g_{\pi\tau} -\partial_\tau g_{\nu\pi})} \object{CHRF\_m\_n\_p }{ [{}_{\mu},_{\nu\pi}] = \frac{1}{2}(\partial_\pi g_{\nu\mu} +\partial_\nu g_{\pi\mu} -\partial_\mu g_{\nu\pi})} \object{CHRT\_m }{ \{{}^\pi_{\pi\mu}\} = \frac{1}{2{\rm det}|g_{\alpha\beta}|}\partial_\mu\left( {\rm det}|g_{\alpha\beta}|\right)} The connection, frame, metric, torsion and nonmetricity are related to each other by the so called structural equations which in the most general case read \begin{eqnarray} && D\theta^a + \Theta^a = 0 \nonumber\\[2mm] && Dg_{ab} + N_{ab} = 0 \label{str0} \end{eqnarray} or in the equivalent ``explicit'' form \begin{equation} \begin{array}{ll} \omega^a{}_b\wedge\theta^b = -t^a,\qquad & t^a=d\theta^a+\Theta^a,\\[2mm] \omega_{ab}+\omega_{ba} = n_{ab},\qquad & n_{ab}=dg_{ab}+N_{ab} \label{str} \end{array} \end{equation} The solution to equations (\ref{str}) are given by the relation \begin{equation} \omega^a{}_b = \frac{1}{2}\left[ -\partial^a\ipr t_b + \partial_b\ipr t^a + n^a{}_b +\big(\partial^a\ipr(\partial_b\ipr t_c-n_{bc}) +\partial_b\ipr n^a{}_c\big)\theta^c\right] \label{solstr} \end{equation} For various specific values of $ \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset ta \begin_inset Formula $ equations (\ref{str}) and (\ref{solstr}) can be used for different purposes. In the most general case (\ref{solstr}) is the {\tt Standard way} to compute connection 1-form $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $. The torsion and nonmetricity are included in these equations depending on the switches \comm{TORSION} and \comm{NONMETR}. The same equation (\ref{solstr}) with $ \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset =dg \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset ta=d \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash theta \end_layout \end_inset a \begin_inset Formula $ is the {\tt Standard way} to find Riemann frame connection $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rim{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $. If torsion is nonzero then $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ can be computed {\tt From contorsion} \begin{equation} \omega^a{}_b = \rim{\omega}{}^a{}_b + \stackrel{\scriptscriptstyle Q}{K}\!{}^a{}_b \label{a1} \end{equation} where $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rim{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ is given by Eq. (\ref{solstr}). Similarly if nonmetricity is nonzero then $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ can be computed {\tt From nonmetricity defect} \begin{equation} \omega^a{}_b = \rim{\omega}{}^a{}_b + \stackrel{\scriptscriptstyle N}{K}\!{}^a{}_b \label{a2} \end{equation} where $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rim{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ is given by Eq. (\ref{solstr}). Finally if both torsion and nonmetricity are nonzero then $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ can be computed {\tt From connection defect} \begin{equation} \omega^a{}_b = \rim{\omega}{}^a{}_b + K^a{}_b \label{a3} \end{equation} where $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rim{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ is given by Eq. (\ref{solstr}). The Riemannian part of connection in Eqs. (\ref{a1}), (\ref{a2}), (\ref{a3}) are directly computed by Eq. (\ref{solstr}) (not via the object \comm{romega}). The contorsion $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptscriptstyle \end_layout \end_inset Q \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset K \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ! \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ is obtained {\tt From torsion} by (\ref{solstr}) with $ \end_inset ta= \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Theta \end_layout \end_inset a \begin_inset Formula $, $ \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset =0 \begin_inset Formula $. The nonmetricity defect $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptscriptstyle \end_layout \end_inset N \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset K \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash ! \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $ is obtained {\tt From nonmetricity} by (\ref{solstr}) with $ \end_inset ta=0 \begin_inset Formula $, $ \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset =N \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. Analogously (\ref{solstr}) with $ \end_inset ta= \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Theta \end_layout \end_inset a \begin_inset Formula $, $ \end_inset n \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset =N \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is the {\tt Standard way} to compute the connection defect $ \end_inset Ka \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset b \begin_inset Formula $. The torsion $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Theta \end_layout \end_inset a \begin_inset Formula $ can be calculated {\tt From contorsion} \begin{equation} \Theta^a = -\stackrel{\scriptscriptstyle Q}{K}\!{}^a{}_b\wedge\theta^b \end{equation} or {\tt From connection defect} \begin{equation} \Theta^a = -K^a{}_b\wedge\theta^b \end{equation} The nonmetricity $ \end_inset N \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be computed {\tt From nonmetricity defect} \begin{equation} N_{ab} = \stackrel{\scriptscriptstyle N}{K}_{ab}+ \stackrel{\scriptscriptstyle N}{K}_{ba} \end{equation} or {\tt From connection defect} \begin{equation} N_{ab} = K_{ab}+K_{ba} \end{equation} \section{Spinorial Connection and Torsion} Spinorial connection is defined in \grg\ iff nonmetricity is zero and switch \comm{NONMETR} is turned off. The upper sign in this section correspond to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ while lower one to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. Spinorial connection is defined by the equation \begin{equation} DX^A_{\dot B} = dX^A{}_{\dot B} \mp\omega^A{}_M\,X^M{}_{\dot B} \pm\omega^{\dot M}{}_{\dot B}\,X^A{}_{\dot M} \end{equation} where due to antisymmetry of the frame connection $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset [ab] \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ we have {\tt Spinorial connection} 1-forms \begin{equation} \omega_{ab} \tsst \epsilon_{AB} \omega_{\dot A\dot B} + \epsilon_{\dot A\dot B} \omega_{AB} \end{equation} \object{Undotted Connection omegau.AB}{\omega_{AB}} \object{Dotted Connection omegad.AB\cc}{\omega_{\dot A\dot B}} The spinorial connection 1-forms $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be calculated {\tt From frame connection} by the standard spinor $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash tsst \end_layout \end_inset \begin_inset Formula $ tensor relation (\ref{asys}). Inversely the frame connection $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be found {\tt From spinorial connection} by relation (\ref{asyt}). Since $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is real the spinorial equivalents $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be computed from each other {\tt By conjugation} \begin{equation} \omega_{\dot A\dot B}=\overline{\omega_{AB}},\qquad \omega_{AB}=\overline{\omega_{\dot A\dot B}} \end{equation} If torsion is nonzero (\comm{TORSION} is on) when we have in addition the {\tt Riemann spinorial connection} \object{Riemann Undotted Connection romegau.AB}{\rim{\omega}_{AB}} \object{Riemann Dotted Connection romegad.AB\cc}{\rim{\omega}_{\dot A\dot B}} The Riemann spinorial connection $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rim{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be calculated by {\tt Standard way} \begin{equation} \stackrel{{\scriptscriptstyle\{\}}}{\omega}_{AB}= \label{ssolver} \pm i*[ d S_{AB}\wedge\theta_{C\dot C} -\epsilon_{C(A} d S_{B)M}\wedge \theta^M_{\ \ \dot C}]\theta^{C\dot C} \end{equation} The conjugated relation is used for $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rim{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The {\tt Spinorial contorsion} 1-forms \object{Undotted Contorsion KU.AB}{\stackrel{\scriptscriptstyle Q}{K}\!{}_{AB}} \object{Dotted Contorsion KD.AB\cc}{\stackrel{\scriptscriptstyle Q}{K}\!{}_{\dot A\dot B}} are the spinorial analogues of the contorsion 1-form \begin{equation} \stackrel{\scriptscriptstyle Q}{K}_{ab} \tsst \epsilon_{AB} \stackrel{\scriptscriptstyle Q}{K}_{\dot A\dot B} + \epsilon_{\dot A\dot B} \stackrel{\scriptscriptstyle Q}{K}_{AB} \end{equation} The spinorial contorsion 1-forms $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptscriptstyle \end_layout \end_inset Q \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset K \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptscriptstyle \end_layout \end_inset Q \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset K \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be calculated {\tt From contorsion} by the standard spinor $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash tsst \end_layout \end_inset \begin_inset Formula $ tensor relation (\ref{asys}). Inversely the contorsion $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptscriptstyle \end_layout \end_inset Q \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset K \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be found {\tt From spinorial contorsion} by relation (\ref{asyt}). The spinorial equivalents $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptscriptstyle \end_layout \end_inset Q \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset K \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptscriptstyle \end_layout \end_inset Q \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset K \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be computed from each other {\tt By conjugation} \begin{equation} \stackrel{\scriptscriptstyle Q}{K}_{\dot A\dot B}=\overline{\stackrel{\scriptscriptstyle Q}{K}_{AB}},\qquad \stackrel{\scriptscriptstyle Q}{K}_{AB}=\overline{\stackrel{\scriptscriptstyle Q}{K}_{\dot A\dot B}} \end{equation} The {\tt Standard way} to find $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is \begin{equation} \omega_{AB} = \rim{\omega}_{AB}+\stackrel{\scriptscriptstyle Q}{K}_{AB} \end{equation} where $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rim{ \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is given directly by Eq. (\ref{ssolver}). The conjugated Eq. is used for $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. \section{Curvature} The curvature 2-form \object{Curvature OMEGA'a.b}{\Omega^a{}_b= \frac{1}{2}R^a_{bcd}\,S^{cd}} can be computed {\tt By standard way} \begin{equation} \Omega^a{}_b = d\omega^a{}_b + \omega^a{}_n \wedge \omega^n{}_b \label{omes} \end{equation} The Riemann curvature tensor is given by the relation \object{Riemann Tensor RIM'a.b.c.d}{R^a{}_{bcd}= \partial_d\ipr\partial_c\ipr\Omega^a{}_b} The Ricci tensor \object{Ricci Tensor RIC.a.b}{R_{ab}} can be computed {\tt From Curvature} \begin{equation} R_{ab} = \partial_b\ipr\partial_m\ipr\Omega^m{}_a \label{rics} \end{equation} or {\tt From Riemann tensor} \begin{equation} R_{ab} = R^m{}_{amb} \end{equation} The \object{Scalar Curvature RR}{R} can be computed {\tt From Ricci Tensor} \begin{equation} R = R_{mn}\,g^{mn} \end{equation} The Einstein tensor is given by the relation \object{Einstein Tensor GT.a.b}{G_{ab}=R_{ab}-\frac{1}{2}g_{ab}R} If nonmetricity is nonzero (\comm{NONMETR} is on) then we have \object{Homothetic Curvature OMEGAH}{\OO{h}} \object{A-Ricci Tensor RICA.a.b}{\RR{A}_{ab}} \object{S-Ricci Tensor RICS.a.b}{\RR{S}_{ab}} They can be calculated {\tt From curvature} by the relations \begin{equation} \OO{h}=\Omega^n{}_n \end{equation} \begin{equation} \RR{A}_{ab}= \partial_b\ipr\partial^m\ipr\Omega_{[ma]} \end{equation} \begin{equation} \RR{S}_{ab}= \partial_b\ipr\partial^m\ipr\Omega_{(ma)} \end{equation} and the scalar curvature can be computed {\tt From A-Ricci tensor} \begin{equation} R = \RR{A}_{mn}g^{mn} \end{equation} \section{Spinorial Curvature} Spinorial curvature is defined in \grg\ iff nonmetricity is zero and switch \comm{NONMETR} is turned off. The upper sign in this section correspond to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ while lower one to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The {\tt Spinorial curvature} 2-forms \object{Undotted Curvature OMEGAU.AB}{\Omega_{AB}} \object{Dotted Curvature OMEGAD.AB\cc}{\Omega_{\dot A\dot B}} is related to the curvature 2-form $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ by the standard relation \begin{equation} \Omega_{ab} \tsst \epsilon_{AB} \Omega_{\dot A\dot B} + \epsilon_{\dot A\dot B} \Omega_{AB} \end{equation} The spinorial curvature 1-forms $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be calculated {\tt From curvature} by the relation (\ref{asys}). The frame curvature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be found {\tt From spinorial curvature} by relation (\ref{asyt}). The $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be computed from each other {\tt By conjugation} \begin{equation} \Omega_{\dot A\dot B}=\overline{\Omega_{AB}},\qquad \Omega_{AB}=\overline{\Omega_{\dot A\dot B}} \end{equation} The {\tt Standard way} to calculate $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is \begin{equation} \Omega_{AB} = d\omega_{AB} \pm \omega_A{}^M\wedge\omega_{MB} \end{equation} The conjugated relation is used for $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. \section{Curvature Decomposition} In general curvature consists of 11 irreducible pieces. If nonmetricity is nonzero then one can perform decomposition \begin{equation} R_{abcd}=\RR{A}_{abcd}+\RR{S}_{abcd},\qquad \RR{A}_{abcd}=R_{[ab]cd},\qquad \RR{S}_{abcd}=R_{(ab)cd} \end{equation} Here the S-part of the curvature vanishes identically if nonmetricity is zero and we consider further decomposition of A and S parts independently. First we consider the A-part of the curvature. It can be decomposed into 6 pieces \begin{equation} \RR{A}_{abcd} = \RR{w}_{abcd}+ \RR{c}_{abcd}+ \RR{r}_{abcd}+ \RR{a}_{abcd}+ \RR{b}_{abcd}+ \RR{d}_{abcd} \end{equation} Here first three terms are the well-known irreducible pieces of the Riemannian curvature while last three terms vanish if torsion is zero. The corresponding 2-forms are \object{Weyl 2-form OMW.a.b } {\OO{w}_{ab} = \frac12 \RR{w}_{abcd}\,S^{cd}} \object{Traceless Ricci 2-form OMC.a.b } {\OO{c}_{ab} = \frac12 \RR{c}_{abcd}\,S^{cd}} \object{Scalar Curvature 2-form OMR.a.b } {\OO{r}_{ab} = \frac12 \RR{r}_{abcd}\,S^{cd}} \object{Ricanti 2-form OMA.a.b } {\OO{a}_{ab} = \frac12 \RR{a}_{abcd}\,S^{cd}} \object{Traceless Deviation 2-form OMB.a.b } {\OO{b}_{ab} = \frac12 \RR{b}_{abcd}\,S^{cd}} \object{Antisymmetric Curvature 2-form OMD.a.b } {\OO{d}_{ab} = \frac12 \RR{d}_{abcd}\,S^{cd}} The {\tt Standard way} to find these quantities is given by the following formulas. \begin{equation} \OO{r}_{ab} = \frac{1}{d(d-1)}R\,S_{ab} \end{equation} \begin{equation} \OO{c}_{ab} = \frac{1}{(d-2)}\left[ C_{am}\,\theta^m\!\wedge\theta_b -C_{bm}\,\theta^m\!\wedge\theta_a\right],\quad C_{ab}=\RR{A}_{(ab)}-\frac{1}{d}g_{ab}R \end{equation} \begin{equation} \OO{a}_{ab} = \frac{1}{(d-2)}\left[ A_{am}\,\theta^m\!\wedge\theta_b -A_{bm}\,\theta^m\!\wedge\theta_a\right],\quad A_{ab}=\RR{A}_{[ab]} \end{equation} \begin{equation} \OO{d}_{ab} = \frac{1}{12}\partial_b\ipr\partial_a\ipr (\OO{A}_{mn}\wedge\theta^m\!\wedge\theta^n) \end{equation} \begin{equation} \OO{b}_{ab} =\frac{1}{2}\left[ \partial_b\ipr(\theta^m\!\wedge\OO{A0}_{am}) -\partial_a\ipr(\theta^m\!\wedge\OO{A0}_{bm}) \right] \end{equation} where \[\OO{A0}_{ab} = \OO{A}_{ab} -\OO{c}_{ab} -\OO{r}_{ab} -\OO{a}_{ab} -\OO{d}_{ab} \] And finally \begin{equation} \OO{w}_{ab} = \OO{A}_{ab} -\OO{c}_{ab} -\OO{r}_{ab} -\OO{a}_{ab} -\OO{b}_{ab} -\OO{d}_{ab} \end{equation} If $ \end_inset d=2 \begin_inset Formula $ then $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash OO{ \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ turns out to be irreducible and coincides with the scalar curvature irreducible piece \begin{equation} \OO{A}_{ab} = \OO{r}_{ab} \end{equation} Now we consider the decomposition of the S curvature part which is nonzero iff nonmetricity is nonzero. First we consider the case $ \end_inset d \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash geq \end_layout \end_inset 3 \begin_inset Formula $. In this case we have 5 irreducible components \begin{equation} \RR{S}_{abcd} = \RR{h}_{abcd}+ \RR{sc}_{abcd}+ \RR{sa}_{abcd}+ \RR{v}_{abcd}+ \RR{u}_{abcd} \end{equation} The corresponding 2-forms are \object{Homothetic Curvature 2-form OSH.a.b } {\OO{h}_{ab} = \frac12 \RR{h}_{abcd}\,S^{cd}} \object{Antisymmetric S-Ricci 2-form OSA.a.b } {\OO{sa}_{ab} = \frac12 \RR{sa}_{abcd}\,S^{cd}} \object{Traceless S-Ricci 2-form OSC.a.b } {\OO{sc}_{ab} = \frac12 \RR{sc}_{abcd}\,S^{cd}} \object{Antisymmetric S-Curvature 2-form OSV.a.b } {\OO{v}_{ab} = \frac12 \RR{v}_{abcd}\,S^{cd}} \object{Symmetric S-Curvature 2-form OSU.a.b } {\OO{u}_{ab} = \frac12 \RR{u}_{abcd}\,S^{cd}} The {\tt Standard way} to compute the decomposition is \begin{equation} \OO{h}_{ab}=-\frac{1}{(d^2-4)}\left[ \theta_a\wedge\partial_b\ipr\OO{h}{} +\theta_b\wedge\partial_a\ipr\OO{h}{} -g_{ab}\OO{h}{}d\right] \end{equation} \begin{equation} \OO{sa}_{ab} =\frac{d}{(d^2-4)}\left[ \theta_a\wedge(\RR{S}_{[bm]}\wedge\theta^m) +\theta_b\wedge(\RR{S}_{[am]}\wedge\theta^m) -\frac{2}{d}g_{ab}\,\RR{S}_{cd}S^{cd}\right] \end{equation} \begin{equation} \OO{sc}_{ab} =\frac{1}{d}\left[ \theta_a\wedge(\RR{S}_{(bm)}\wedge\theta^m) +\theta_b\wedge(\RR{S}_{(am)}\wedge\theta^m)\right] \label{ccc} \end{equation} \begin{equation} \OO{v}_{ab} = \frac{1}{4}\left[ \partial_a\ipr(\OO{S0}_{bm}\wedge\theta^m) +\partial_b\ipr(\OO{S0}_{am}\wedge\theta^m)\right] \end{equation} where \[\OO{S0}_{ab} = \OO{S}_{ab} -\OO{h}_{ab} -\OO{sa}_{ab} -\OO{sc}_{ab} \] And finally \begin{equation} \OO{u}_{ab} = \OO{S}_{ab} -\OO{h}_{ab} -\OO{sa}_{ab} -\OO{sc}_{ab} -\OO{v}_{ab} \end{equation} If $ \end_inset d=2 \begin_inset Formula $ then only the h- and sc-components are nonzero. The $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash OO{ \end_layout \end_inset sc \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ are given by (\ref{ccc}) and \begin{equation} \OO{h}_{ab} = \OO{S}_{ab}-\OO{sc}_{ab} \end{equation} \begin{center} \begin{tabular}{|c|c|c|} \hline object & exists if & and has $n$ components \\ \hline \vv$R_{abcd}$ & & $\frac{d^3(d-1)}{2}$ \\[1mm] \hline\vv$\rim{R}{}_{abcd}$ & & $\frac{d^2(d^2-1)}{12}$ \\[1mm] \hline\vv$\RR{A}_{abcd}$ & & $\frac{d^2(d-1)^2}{4}$ \\[1mm] \hline\vv$\RR{S}_{abcd}$ & & $\frac{d^2(d^2-1)}{4}$ \\[1mm] \hline\vv$\RR{w}_{abcd}$ & $d\geq4$ & $\frac{d(d+1)(d+2)(d-3)}{12}$ \\ \vv$\RR{c}_{abcd}$ & $d\geq3$ & $\frac{(d+2)(d-1)}{2}$ \\ \vv$\RR{r}_{abcd}$ & & $1$ \\[1mm] \hline\vv$\RR{a}_{abcd}$ & $d\geq3$ & $\frac{d(d-1)}{2}$ \\ \vv$\RR{b}_{abcd}$ & $d\geq4$ & $\frac{d(d-1)(d+2)(d-3)}{8}$ \\ \vv$\RR{d}_{abcd}$ & $d\geq4$ & $\frac{d(d-1)(d-2)(d-3)}{24}$ \\[1mm] \hline\vv$\RR{h}_{abcd}$ & & $\frac{d(d-1)}{2}$ \\ \vv$\RR{sa}_{abcd}$ & $d\geq3$ & $\frac{d(d-1)}{2}$ \\ \vv$\RR{sc}_{abcd}$ & & $\frac{(d+2)(d-1)}{2}$ \\ \vv$\RR{v}_{abcd}$ & $d\geq4$ & $\frac{d(d+2)(d-1)(d-3)}{8}$ \\ \vv$\RR{u}_{abcd}$ & $d\geq3$ & $\frac{(d-2)(d+4)(d^2-1)}{8}$ \\[1mm] \hline \end{tabular} \end{center} \section{Spinorial Curvature Decomposition} Spinorial curvature is defined in \grg\ iff nonmetricity is zero and switch \comm{NONMETR} is turned off. The upper sign in this section correspond to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ while lower one to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. Let us introduce the spinorial analog of the curvature tensor \begin{eqnarray} R_{abcd}&\tsst& \ \ R_{ABCD}\epsilon_{\dot{A}\dot{B}}\epsilon_{\dot{C}\dot{D}} +R_{\dot{A}\dot{B}\dot{C}\dot{D}}\epsilon_{AB}\epsilon_{CD} \nonumber\\[1mm] &&+R_{AB\dot{C}\dot{D}}\epsilon_{\dot{A}\dot{B}}\epsilon_{CD} +R_{\dot{A}\dot{B} CD}\epsilon_{AB}\epsilon_{\dot{C}\dot{D}}, \\[1.5mm] R_{ABCD}&=&-i*(\Omega_{AB}\wedge S_{CD}),\ \ R_{AB\dot{C}\dot{D}}\ =\ i*(\Omega_{AB}\wedge S_{\dot{C}\dot{D}})\\[1.5mm] R_{\dot{A}\dot{B}\dot{C}\dot{D}}&=&\overline{R_{ABCD}},\ \ R_{\dot{A}\dot{B} CD}\ =\ \overline{R_{AB\dot{C}\dot{D}}} \end{eqnarray} The quantities $ \end_inset R \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ABCD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset R \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset C \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset D \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be used to compute the {\tt Curvature spinors} ($ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash equiv \end_layout \end_inset \begin_inset Formula $ {\tt Curvature components}) \object{Weyl Spinor RW.ABCD}{C_{ABCD}} \object{Traceless Ricci Spinor RC.AB.CD\cc}{C_{AB\dot C\dot D}} \object{Scalar Curvature RR}{R} \object{Ricanti Spinor RA.AB}{A_{AB}} \object{Traceless Deviation Spinor RB.AB.CD\cc}{B_{AB\dot C\dot D}} \object{Scalar Deviation RD}{D} All these spinors are irreducible (totally symmetric). Weyl spinor $ \end_inset C \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ABCD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ {\tt From spinor curvature} is \begin{eqnarray} C_{abcd}&\tsst& C_{ABCD}\epsilon_{\dot{A}\dot{B}}\epsilon_{\dot{C}\dot{D}} +C_{\dot{A}\dot{B}\dot{C}\dot{D}}\epsilon_{AB}\epsilon_{CD} \\[1mm] C_{ABCD}&=&R_{(ABCD)} \label{RW} \end{eqnarray} Traceless Ricci spinor $ \end_inset C \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ {\tt From spinor curvature} is \begin{eqnarray} C_{ab}&\tsst&C_{AB\dot{A}\dot{B}}\\[2mm] C_{AB\dot{C}\dot{D}}&=&\pm(R_{AB\dot{C}\dot{D}}+R_{\dot{C}\dot{D} AB}) \end{eqnarray} Scalar curvature {\tt From spinor curvature} is \begin{equation} R=2(R^{MN}_{\ \ \ \ MN}+R^{\dot{M}\dot{N}}_{\ \ \ \ \dot{M}\dot{N}}) \end{equation} Antisymmetric Ricci spinor $ \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ {\tt From spinor curvature} is \begin{eqnarray} A_{ab}&\tsst& A_{AB}\epsilon_{\dot{A}\dot{B}}+A_{\dot{A}\dot{B}}\epsilon_{AB}\\[1mm] A_{AB}&=&\mp R^{\ \ \ \,M}_{(A|\ \ M|B)} \end{eqnarray} Traceless deviation spinor $ \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ {\tt From spinor curvature} is \begin{eqnarray} B_{ab}&\tsst&B_{AB\dot{A}\dot{B}}\\[1mm] B_{AB\dot{C}\dot{D}}&=&\pm i(R_{AB\dot{C}\dot{D}}-R_{\dot{C}\dot{D} AB}) \end{eqnarray} Deviation trace {\tt From spinor curvature} is \begin{equation} D=-2i(R^{MN}_{\ \ \ \ MN}-R^{\dot{M}\dot{N}}_{\ \ \ \ \dot{M}\dot{N}}) \end{equation} Note that spinors $ \end_inset C \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset ,B \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset B \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ are Hermitian \begin{equation} C_{AB\dot{C}\dot{D}}=\overline{C_{CD\dot{A}\dot{B}}},\ \ B_{AB\dot{C}\dot{D}}=\overline{B_{CD\dot{A}\dot{B}}} \end{equation} Finally we introduce the decomposition for the spinorial curvature 2-form \begin{equation} \Omega_{AB}= \OO{w}_{AB}+\OO{c}_{AB}+\OO{r}_{AB} +\OO{a}_{AB}+\OO{b}_{AB}+\OO{c}_{AB} \end{equation} where the {\tt Undotted curvature 2-forms} \object{Undotted Weyl 2-form OMWU.AB }{\OO{w}_{AB}} \object{Undotted Traceless Ricci 2-form OMCU.AB }{\OO{c}_{AB}} \object{Undotted Scalar Curvature 2-form OMRU.AB }{\OO{r}_{AB}} \object{Undotted Ricanti 2-form OMAU.AB }{\OO{a}_{AB}} \object{Undotted Traceless Deviation 2-form OMBU.AB }{\OO{b}_{AB}} \object{Undotted Scalar Deviation 2-form OMDU.AB }{\OO{d}_{AB}} are given by \begin{eqnarray} \OO{w}_{AB}&=&C_{ABCD}S^{CD} \\[1mm] \OO{c}_{AB}&=&\pm\frac12 C_{AB\dot{C}\dot{D}}S^{\dot{C}\dot{D}} \\[1mm] \OO{r}_{AB}&=&\frac1{12}S_{AB}R \\[1mm] \OO{a}_{AB}&=&\pm A_{(A}^{\ \ \ M}S_{M|B)} \\[1mm] \OO{b}_{AB}&=&\mp\frac{i}2 B_{AB\dot{C}\dot{D}}S^{\dot{C}\dot{D}} \\[1mm] \OO{d}_{AB}&=&\frac{i}{12}S_{AB}D \end{eqnarray} \section{Torsion Decomposition} The torsion tensor \begin{equation} Q_{abc}=Q_{a[bc]},\qquad \Theta^a=\frac{1}{2}Q^a{}_{bc}\,S^{bc} \end{equation} consists of three irreducible pieces \begin{equation} Q_{abc} = \stackrel{\rm c}{Q}_{abc} +\stackrel{\rm t}{Q}_{abc} +\stackrel{\rm a}{Q}_{abc} \end{equation} \begin{center} \begin{tabular}{|c|c|c|} \hline object & exists if & and has $n$ components \\ \hline \vv$Q_{abc}$ & & $\frac{d^2(d-1)}{2}$ \\[1mm] \hline\vv$\stackrel{\rm c}{Q}_{abc}$ & $d\geq3$ & $\frac{d(d^2-4)}{3}$ \\ \vv$\stackrel{\rm t}{Q}_{abc}$ & & $d$ \\ \vv$\stackrel{\rm a}{Q}_{abc}$ & $d\geq3$ & $\frac{d(d-1)(d-2)}{6}$ \\[1mm] \hline \end{tabular} \end{center} The corresponding union of three objects {\tt Torsion 2-forms} is \object{Traceless Torsion 2-form THQC'a} {\stackrel{\rm c}{\Theta}\!{}^a=\frac{1}{2} \stackrel{\rm c}{Q}\!{}^a{}_{bc}\,S^{bc}} \object{Torsion Trace 2-form THQT'a} {\stackrel{\rm t}{\Theta}\!{}^a=\frac{1}{2} \stackrel{\rm t}{Q}\!{}^a{}_{bc}\,S^{bc}} \object{Antisymmetric Torsion 2-form THQA'a} {\stackrel{\rm a}{\Theta}\!{}^a=\frac{1}{2} \stackrel{\rm a}{Q}\!{}^a{}_{bc}\,S^{bc}} And the auxiliary quantities \object{Torsion Trace QT'a}{Q^a} \object{Torsion Trace 1-form QQ}{Q=-\partial_a\ipr\Theta^a} \object{Antisymmetric Torsion 3-form QQA}{\stackrel{\rm a}{Q}=\theta_a\wedge\Theta^a} The torsion trace $ \end_inset Qa=Qm \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset am \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ can be obtained {\tt From torsion trace 1-form} \begin{equation} Q^a = \partial^a\ipr Q \end{equation} The {\tt Standard way} for the irreducible torsion 2-forms is \begin{equation} \stackrel{\rm t}{\Theta}\!{}^a = -\frac{1}{(d-1)}\theta^a\wedge Q \end{equation} \begin{equation} \stackrel{\rm t}{\Theta}\!{}^a = \frac{1}{3}\partial^a\ipr\stackrel{\rm a}{Q} \end{equation} \begin{equation} \stackrel{\rm c}{\Theta}\!{}^a = \Theta^a -\stackrel{\rm t}{\Theta}\!{}^a -\stackrel{\rm a}{\Theta}\!{}^a \end{equation} The rest of this section is valid in dimension 4 only. In this case one can introduce the torsion pseudo trace \object{Torsion Pseudo Trace QP'a}{ P^a = \stackrel{*}{Q}\!{}^{ma}{}_{m}, \ \stackrel{*}{Q}\!{}^a{}_{bc} = \frac{1}{2}{\cal E}_{bc}{}^{pq} Q^a{}_{pq}} which can be computed {\tt From antisymmetric torsion 3-form} \begin{equation} P^a = \partial^a\ipr\,*\!\stackrel{\rm a}{Q} \end{equation} Finally let us consider the spinorial representation of the torsion. Below the upper sign corresponds to the \seethis{See \pref{spinors}\ or \ref{spinors1}.} signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and lower one to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. First we introduce the spinorial analog of the torsion tensor \begin{equation} Q_{abc}\tsst Q_{A\dot{A} BC}\epsilon_{\dot{B}\dot{C}} +Q_{A\dot{A}\dot{B}\dot{C}}\epsilon_{BC} \end{equation} where \begin{equation} Q_{A\dot{A} BC}=-i*(\Theta_{A\dot{A}}\wedge S_{BC}),\qquad Q_{A\dot{A}\dot{B}\dot{C}}=i*(\Theta_{A\dot{A}}\wedge S_{\dot{B}\dot{C}}) \end{equation} These spinors are reducible but the \object{Traceless Torsion Spinor QC.ABC.D\cc}{C_{ABC\dot D}} \[\stackrel{\rm c}{Q}_{abc}\tsst C_{ABC\dot A}\epsilon_{\dot{B}\dot{C}} +Q_{\dot{A}\dot{B}\dot{C}A}\epsilon_{BC},\quad C_{\dot{A}\dot{B}\dot{C} A}=\overline{C_{ABC\dot{A}}} \] is irreducible (symmetric in $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset ABC \begin_inset Formula $). And it can be computed {\tt From torsion} by the relation \begin{equation} C_{ABC\dot A} = Q_{(A|\dot{A}|BC)} \end{equation} The torsion trace can be calculated {\tt From torsion using spinors} \begin{equation} Q^a\tsst Q^{A\dot{A}},\quad Q_{A\dot{B}}=\mp(Q^M{}_{\dot{B}MA}+Q_A{}^{\dot M}{}_{\dot M\dot{B}}) \end{equation} And similarly the torsion pseudo-trace can be found {\tt From torsion using spinors} \begin{equation} P^a\tsst P^{A\dot{A}},\quad P_{A\dot{B}}=\mp i(Q^M{}_{\dot{B}MA}-Q_A{}^{\dot M}{}_{\dot M\dot{B}}) \end{equation} Finally we introduce the {\tt Undotted trace 2-forms} which are selfdual parts of the irreducible torsion 2-forms \object{Undotted Traceless Torsion 2-form THQCU'a} {\stackrel{\rm c}{\vartheta}\!{}^a} \object{Undotted Torsion Trace 2-form THQTU'a} {\stackrel{\rm t}{\vartheta}\!{}^a} \object{Undotted Antisymmetric Torsion 2-form THQAU'a} {\stackrel{\rm a}{\vartheta}\!{}^a} \seethis{See \pref{thetau}.} These quantities will be used in the gravitational equations. This complex 2-forms can be obtained by the equations ({\tt Standard way}): \begin{eqnarray} \stackrel{\rm c}{\vartheta}\!{}^a &\tsst& \stackrel{\rm c}{\vartheta}\!{}^{A\dot A} =C^A_{\ \ BC}{}^{\dot{A}}S^{BC}\\[1mm] \stackrel{\rm t}{\vartheta}\!{}^a &\tsst& \stackrel{\rm t}{\vartheta}\!{}^{A\dot A} =\mp\frac13 Q_{M}^{\ \ \ \dot{A}}S^{AM}\\[1mm] \stackrel{\rm a}{\vartheta}\!{}^a &\tsst& \stackrel{\rm a}{\vartheta}\!{}^{A\dot A} =\pm\frac{i}3 P_{M}^{\ \ \ \dot{A}}S^{AM} \end{eqnarray} \section{Nonmetricity Decomposition} In general the nonmetricity tensor \begin{equation} N_{abc}=N_{(ab)c},\qquad N_{ab}=N_{abc}\theta^c \end{equation} consist of 4 irreducible pieces \begin{equation} N_{abcd} = \stackrel{\rm c}{N}_{abc} +\stackrel{\rm a}{N}_{abc} +\stackrel{\rm t}{N}_{abc} +\stackrel{\rm w}{N}_{abc} \end{equation} \begin{center} \begin{tabular}{|c|c|c|} \hline object & exists if & and has $n$ components \\ \hline \vv$N_{abc}$ & & $\frac{d^2(d+1)}{2}$ \\[1mm] \hline\vv$\stackrel{\rm c}{N}_{abc}$ & & $\frac{d(d-1)(d+4)}{6}$ \\ \vv$\stackrel{\rm a}{N}_{abc}$ & $d\geq3$ & $\frac{d(d^2-4)}{3}$ \\ \vv$\stackrel{\rm t}{N}_{abc}$ & & $d$ \\ \vv$\stackrel{\rm w}{N}_{abc}$ & & $d$ \\[1mm] \hline \end{tabular} \end{center} The corresponding union of objects {\tt Nonmetricity 1-forms} consist of \object{Symmetric Nonmetricity 1-form NC.a.b} {\stackrel{\rm c}{N}_{ab}=\stackrel{\rm c}{N}_{abc}\theta^c} \object{Antisymmetric Nonmetricity 1-form NA.a.b} {\stackrel{\rm a}{N}_{ab}=\stackrel{\rm a}{N}_{abc}\theta^c} \object{Nonmetricity Trace 1-form NT.a.b} {\stackrel{\rm t}{N}_{ab}=\stackrel{\rm t}{N}_{abc}\theta^c} \object{Weyl Nonmetricity 1-form NW.a.b} {\stackrel{\rm w}{N}_{ab}=\stackrel{\rm w}{N}_{abc}\theta^c} We have also two auxiliary 1-forms \object{Weyl Vector NNW}{\stackrel{\rm w}{N}} \object{Nonmetricity Trace NNT}{\stackrel{\rm t}{N}} They are computed according to the following formulas \begin{equation} \stackrel{\rm w}{N} = N^a{}_a \end{equation} \begin{equation} \stackrel{\rm t}{N} = \theta^a\,\partial^b\ipr N_{ab} - \frac{1}{d} \stackrel{\rm w}{N} \end{equation} \begin{equation} \stackrel{\rm w}{N}_{ab} = \frac{1}{d}g_{ab}\stackrel{\rm w}{N} \end{equation} \begin{equation} \stackrel{\rm t}{N}_{ab}=\frac{d}{(d-1)(d+2)}\left[ \theta_b\partial_a\ipr\stackrel{\rm t}{N} +\theta_a\partial_b\ipr\stackrel{\rm t}{N} -\frac{2}{d} g_{ab} \stackrel{\rm t}{N}\right] \end{equation} \begin{equation} \stackrel{\rm a}{N}_{ab}=\frac{1}{3}\left[ \partial_a\ipr(\theta^m\wedge\stackrel{0}{N}_{bm}) +\partial_b\ipr(\theta^m\wedge\stackrel{0}{N}_{am})\right] \end{equation} where \[\stackrel{\rm 0}{N}_{ab}= N_{abc} -\stackrel{\rm t}{N}_{abc} -\stackrel{\rm w}{N}_{abc} \] And finally \begin{equation} \stackrel{\rm c}{N}_{ab}= N_{abc} -\stackrel{\rm a}{N}_{abc} -\stackrel{\rm t}{N}_{abc} -\stackrel{\rm w}{N}_{abc} \end{equation} \section{Newman-Penrose Formalism} The method of spinorial differential forms described in the previous sections are essentially equivalent to the well known Newman-Penrose formalism but for the sake of convenience \grg\ has complete set of macro objects which allows to write the Newman-Penrose equations in traditional notation. All these objects refer (up to some sign and 1/2 factors) to other \grg\ built-in objects. In this section upper sign corresponds to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and lower one to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. \seethis{See \pref{spinors}.} The frame must be null as explained in section \ref{spinors}. For the Newman-Penrose formalism we use notation and conventions of the book \emph{Exact Solutions of the Einstein Field Equations} by D. Kramer, H. Stephani, M. MacCallum and E. Herlt, ed. E. Schmutzer (Berlin, 1980). We denote this book as ESEFE. We chose the relationships between NP null tetrad and \grg\ null frame as follows \begin{equation} l^\mu=h^\mu_0,\quad k^\mu=h^\mu_1,\quad \overline{m}\!{}^\mu=h^\mu_2,\quad m^\mu=h^\mu_3 \end{equation} The NP vector operators are just the components of the vector frame $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash partial \end_layout \end_inset a \begin_inset Formula $ \begin{eqnarray} \mbox{\tt DD}&=& D =\partial_1 \\ \mbox{\tt DT}&=& \Delta=\partial_0 \\ \mbox{\tt du}&=& \delta=\partial_3 \\ \mbox{\tt dd}&=& \overline\delta=\partial_2 \end{eqnarray} The spin coefficient are the components of the connection 1-form \object{SPCOEF.AB.c}{ \omega_{AB\,c}=\partial_c\ipr\omega_{AB}} or in the NP notation \begin{eqnarray} \mbox{\tt alphanp }&=& \alpha =\pm\omega_{(1)2} \\ \mbox{\tt betanp }&=& \beta =\pm\omega_{(1)3} \\ \mbox{\tt gammanp }&=& \gamma =\pm\omega_{(1)0} \\ \mbox{\tt epsilonnp }&=& \epsilon =\pm\omega_{(1)1} \\ \mbox{\tt kappanp }&=& \kappa =\pm\omega_{(0)1} \\ \mbox{\tt rhonp }&=& \rho =\pm\omega_{(0)2} \\ \mbox{\tt sigmanp }&=& \sigma =\pm\omega_{(0)3} \\ \mbox{\tt taunp }&=& \tau =\pm\omega_{(0)0} \\ \mbox{\tt munp }&=& \mu =\pm\omega_{(2)3} \\ \mbox{\tt nunp }&=& \nu =\pm\omega_{(2)0} \\ \mbox{\tt lambdanp }&=& \lambda =\pm\omega_{(2)2} \\ \mbox{\tt pinp }&=& \pi =\pm\omega_{(2)1} \\ \end{eqnarray} where the first index of the quantity $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset (AB)c \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is included inn parentheses to remind that it is summed spinorial index. Finally for the curvature we have \object{PHINP.AB.CD\cc }{ \Phi_{AB\dot{C}\dot{D}} = \pm\frac{1}{2}C_{AB\dot C\dot D} } \object{PSINP.ABCD }{\Psi_{ABCD}=C_{ABCD}} the conventions for the scalar curvature $ \end_inset R \begin_inset Formula $ in ESEFE and in \grg\ are the same. For the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ the Newman-Penrose equations for the quantities introduced above can be found in section 7.1 of ESEFE. For other signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ one must alter the sign of $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Psi \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ABCD \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Phi \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset C \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash dot \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset D \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset R \begin_inset Formula $ in Eqs. (7.28)--(7.45). \section{Electromagnetic Field} Formulas in this section are valid only in spaces with the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,…,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,…,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The sign factor $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset \begin_inset Formula $ in the expressions below is $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset =- \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset diag \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset 0 \begin_inset Formula $ ($ \end_inset +1 \begin_inset Formula $ for the first signature and $ \end_inset -1 \begin_inset Formula $ for the second). Let us introduce the \object{EM Potential A}{A=A_\mu dx^\mu} and the \object{Current 1-form J}{J=j_\mu dx^\mu} The EM strength tensor $ \end_inset F \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash alpha \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash beta \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash partial \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash alpha \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash beta \end_layout \end_inset - \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash partial \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash beta \end_layout \end_inset A \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash alpha \end_layout \end_inset \begin_inset Formula $ \object{EM Tensor FT.a.b}{F_{ab}= \partial_b\ipr\partial_a\ipr F} where $ \end_inset F \begin_inset Formula $ is the \object{EM 2-form FF}{F} which can be found {\tt From EM potential} \begin{equation} F=dA \end{equation} or {\tt From EM tensor} \begin{equation} F = \frac{1}{2}F_{ab}\,S^{ab} \end{equation} The EM action $ \end_inset d \begin_inset Formula $-form \object{EM Action EMACT}{L_{\rm EM}= -\frac{1}{8\pi}\,F\wedge *F} The {\tt Maxwell Equations} \object{First Maxwell Equation MWFq}{d*F=-4\pi\sigma\,(-1)^{d}\,*J} \object{Second Maxwell Equation MWSq}{dF=0} The current must satisfy the \object{Continuity Equation COq}{d*J=0} The \object{EM Energy-Momentum Tensor TEM.a.b}{T_{ab}^{\rm EM}} is given by the equation \begin{equation} T^{\rm EM}_{ab} = \frac{\sigma}{4\pi} F_{am}F_b{}^m +s\sigma\,g_{ab}\,*L_{\rm EM} \end{equation} The rest of the section is valid in the dimension 4 only. In 4 dimensions the tensor $ \end_inset F \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and its dual $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash stackrel \end_layout \end_inset * \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset F \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash frac \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset 1 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset 2 \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash cal \end_layout \end_inset E \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset mn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset F \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset mn \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ are expressed via usual 3-dimensional vectors $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash vec \end_layout \end_inset E \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash vec \end_layout \end_inset H \begin_inset Formula $ \begin{eqnarray} F_{ab}&=&-\sigma\left(\begin{array}{rrr} E_1&E_2&E_3\\ &-H_3&H_2\\ &&-H_1\end{array}\right)\\[1.5mm] \stackrel{*}{F}_{ab}&=&\sigma\left(\begin{array}{rrr} H_1&H_2&H_3\\ &E_3&-E_2\\ &&E_1\end{array}\right) \end{eqnarray} Similarly for the current we have \begin{equation} J=\sigma(-\rho dt + \vec j\,d\vec x) \end{equation} The {\tt EM scalars} \object{First EM Scalar SCF}{I_1=\frac12F_{ab}F^{ab} ={\vec H}^2-{\vec E}^2} \object{Second EM Scalar SCS}{I_2=\frac12\stackrel{*}{F}_{ab}F^{ab} =2\vec E\cdot\vec H} can be obtained as follows by {\tt Standard way} \begin{equation} I_1 = -*(F\wedge*F) \end{equation} \begin{equation} I_2 = *(F\wedge F) \end{equation} The \object{Complex EM 2-form FFU}{\Phi} can be found {\tt From EM 2-form} \begin{equation} \Phi=F-i*F \end{equation} or {\tt From EM Spinor} \begin{equation} \Phi = 2\Phi_{AB}\,S^{AB} \end{equation} The 2-form $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Phi \end_layout \end_inset \begin_inset Formula $ must obey the \object{Selfduality Equation SDq.AB\cc}{\Phi\wedge S_{\dot A\dot B}} and gives rise to the \object{Complex Maxwell Equation MWUq}{d\Phi=-4i\sigma\pi\,*J} The EM 2-form $ \end_inset F \begin_inset Formula $ can be restored {\tt From Complex EM 2-form} \begin{equation} F=\frac{1}{2}(\Phi+\overline\Phi) \end{equation} The symmetric \object{Undotted EM Spinor FIU.AB}{\Phi_{AB}} is the spinorial analog of the tensor $ \end_inset F \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ \begin{equation} F_{ab} \tsst \epsilon_{AB} \Phi_{\dot A\dot B} + \epsilon_{\dot A\dot B} \Phi_{AB} \end{equation} It can be obtained either {\tt From complex EM 2-form} \begin{equation} \Phi_{AB} = -\frac{i}{2}*(\Phi\wedge S_{AB}) \end{equation} of {\tt From EM 2-form} \begin{equation} \Phi_{AB} = -i*(F\wedge S_{AB}) \end{equation} The \object{Complex EM Scalar SCU}{\iota=I_1-iI_2} can be found {\tt From EM Spinor} \begin{equation} \iota = 2\Phi_{AB}\Phi^{AB} \end{equation} or {\tt From Complex EM 2-form} \begin{equation} \iota = -\frac{i}{2} *(\Phi\wedge\Phi) \end{equation} Finally we have the \object{EM Energy-Momentum Spinor TEMS.AB.CD\cc} {T^{\rm EM}_{AB\dot A\dot B}=\frac{1}{2\pi}\Phi_{AB}\Phi_{\dot A\dot B}} \section{Dirac Field} In this section upper sign corresponds to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and lower one to the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The four component Dirac spinor consists of two 1-index spinors \begin{equation} \psi=\left(\begin{array}{c}\phi^A\\ \chi_{\dot A}\end{array}\right),\ \ \overline\psi=\left(\chi_A\ \ \phi^{\dot A}\right) \end{equation} Thus we have the {\tt Dirac spinor} as the union of two objects \object{Phi Spinor PHI.A}{\phi_A} \object{Chi Spinor CHI.B}{\chi_B} The gamma-matrices are expressed via sigma-matrices as follows \begin{equation} \gamma^m=\sqrt2\left(\begin{array}{cc} 0&\sigma^{mA\dot B}\\ \sigma^m\!{}_{B\dot A}&0\end{array}\right) \end{equation} Dirac field action 4-form \begin{eqnarray} &&\mbox{\tt Dirac Action 4-form DACT}=L_{\rm D}=\nonumber\\[1mm] &&\quad=\left[\frac{i}2(\overline\psi\gamma^a (\nabla_a+ieA_a)\psi-(\nabla_a-ieA_a)\overline\psi\gamma^a\psi) -m_{\rm D}\overline\psi\psi\right]\upsilon \end{eqnarray} The {\tt Standard way} to compute this quantity is \begin{eqnarray} L_{\rm D} &=& -\frac{i}{\sqrt2}\left[ \phi_{\dot A}\theta^{A\dot A}\!\wedge*(D+ieA)\phi_A-{\rm c.c.} -\chi_{\dot A} \theta^{A\dot A}\!\wedge*(D-ieA)\chi_A -{\rm c.c.}\right]- \nonumber\\[1mm]&&\qquad\qquad\quad -m_{\rm D}\left(\phi^A\chi_A+{\rm c.c.}\right)\upsilon \end{eqnarray} The {\tt Dirac equation} is \object{Phi Dirac Equation DPq.A\cc}{ i\sqrt2\partial_{B\dot A}\ipr(D+ieA-\frac12Q)\phi^B-m_{\rm D}\chi_{\dot A}=0} \object{Chi Dirac Equation DCq.A\cc}{ i\sqrt2\partial_{B\dot A}\ipr(D-ieA-\frac12Q)\chi^B-m_{\rm D}\phi_{\dot A}=0} where $ \end_inset Q \begin_inset Formula $ is the torsion trace 1-form. Notice that terms with the electromagnetic field $ \end_inset eA \begin_inset Formula $ are included in equations iff the value of $ \end_inset A \begin_inset Formula $ is defined. The unit charge $ \end_inset e \begin_inset Formula $ is given by the constant \comm{ECONST}. The current 1-form can be computed {\tt From Dirac Spinor} \begin{equation} J=\mp\sqrt2e(\phi_A\phi_{\dot A}+\chi_A\chi_{\dot A})\theta^{A\dot A} \end{equation} The symmetrized \object{Dirac Energy-Momentum Tensor TDI.a.b}{T^{\rm D}_{ab}} can be obtained as follows \begin{eqnarray} T^{\rm D}_{ab}&=& *(\theta_{(a}\wedge T^{\rm D}_{b)})\nonumber\\[1mm] T^{\rm D}_a&=&\mp\frac{i}{\sqrt2}\Big[ *\theta^{A\dot A}\partial_a\ipr(D+ieA)\phi_A\phi_{\dot A} -{\rm c.c.}\nonumber\\ &&\qquad-*\theta^{A\dot A}\partial_a\ipr(D-ieA)\chi_A\chi_{\dot A} -{\rm c.c.}\Big] \pm\partial_a\ipr L_{\rm D} \end{eqnarray} The \object{Undotted Dirac Spin 3-Form SPDIU.AB}{s^{\rm D}_{AB}} \begin{equation} s^{\rm D}_{AB}=\frac{i}{2\sqrt2} \left(*\theta_{(A|\dot A}\phi_{B)}\phi^{\dot A} -*\theta_{(A|\dot A}\chi_{B)}\chi^{\dot A}\right) \end{equation} The Dirac field mass $ \end_inset m \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset D \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is given by the constant \comm{DMASS}. \section{Scalar Field} Formulas in this section are valid in any dimension with the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,…,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,…,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The sign factor $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset \begin_inset Formula $ is $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset =- \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset diag \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset 0 \begin_inset Formula $ ($ \end_inset +1 \begin_inset Formula $ for the first signature and $ \end_inset -1 \begin_inset Formula $ for the second). The scalar field \object{Scalar Field FI}{\phi} The minimal scalar field action $ \end_inset d \begin_inset Formula $-form \object{Minimal Scalar Action SACTMIN}{ L_{\rm Smin}= -\frac{1}{2}\left[\sigma(\partial_\alpha\phi)^2+ m_{\rm s}^2 \phi^2\right]\upsilon} The nonminimal scalar field action \object{Scalar Action SACT}{ L_{\rm S}= -\frac{1}{2}\left[\sigma(\partial_\alpha\phi)^2+ (m_{\rm s}^2+a_0R) \phi^2\right]\upsilon} The scalar field equation \object{Scalar Equation SCq} {s\sigma(-1)^d*d*d\phi-(m_{\rm s}^2+a_0R)\phi=0} which gives \[-\sigma\rim{\nabla}{}^\pi\rim{\nabla}_\pi\phi-(m_{\rm s}^2+a_0R)\phi=0 \] The minimal energy-momentum tensor is \begin{eqnarray} &&\mbox{\tt Minimal Scalar Energy-Momentum Tensor TSCLMIN.a.b} =T^{\rm Smin}_{ab}= \nonumber\\ &&\qquad\qquad=\partial_a\phi\partial_b\phi+s\sigma\,g_{ab} *L_{\rm Smin} \end{eqnarray} The nonminimal part of the scalar field energy-momentum \seethis{See pages \pageref{graveq}\ and \pageref{metreq}.} tensor can be taken into account in the left-hand side of gravitational equations. The scalar field mass $ \end_inset m \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset s \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ are given by the constant {\tt SMASS}. The nonminimal interaction terms are included iff the switch \comm{NONMIN} \swind{NONMIN} is turned on and the value of nonminimal interaction constant $ \end_inset a0 \begin_inset Formula $ is determined by the object \object{A-Constants ACONST.i2}{a_i} The default value of $ \end_inset a0 \begin_inset Formula $ is the constant \comm{AC0}. \section{Yang-Mills Field} Formulas in this section are valid in any dimension with the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,…,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,…,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The sign factor $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset \begin_inset Formula $ in the expressions below is $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset =- \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset diag \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset 0 \begin_inset Formula $ ($ \end_inset +1 \begin_inset Formula $ for the first signature and $ \end_inset -1 \begin_inset Formula $ for the second). The indices $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset i,j,k,l,m,n \begin_inset Formula $ are the internal space Yang-Mills indices and we a assume that the internal Yang-Mills metric is $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash delta \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ij \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. The Yang-Mills potential 1-form \object{YM Potential AYM.i9}{A^i=A^i_\mu dx^\mu} The structural constants \object{Structural Constants SCONST.i9.j9.k9}{c^i{}_{jk}=c^i{}_{[jk]}} The Yang-Mills strength 2-form \object{YM 2-form FFYM.i9}{F^i} and strength tensor \object{YM Tensor FTYM.i9.a.b}{F^i{}_{ab}} The $ \end_inset Fi \begin_inset Formula $ can be computed {\tt From YM potential} \begin{equation} F^i = dA^i + \frac12 c^i{}_{jk} \, A^j\wedge A^k \end{equation} or {\tt From YM tensor} \begin{equation} F^i = \frac12 F^i{}_{ab}\, S^{ab} \end{equation} The {\tt Standard way} to find Yang-Mills strength tensor is \begin{equation} F^i{}_{ab}=\partial_b\ipr\partial_a\ipr F^i \end{equation} The Yang-Mills action $ \end_inset d \begin_inset Formula $-form \object{YM Action YMACT}{L_{\rm YM}= -\frac{1}{8\pi}F^i\wedge*F_i} The {\tt YM Equations} \object{First YM Equation YMFq.i9}{d*F^i + c^i{}_{jk} \, A^j\wedge *F^k=0} \object{Second YM Equation YMSq.i9}{dF^i + c^i{}_{jk} \, A^j\wedge F^k=0} The energy-momentum tensor \object{YM Energy-Momentum Tensor TYM.a.b} {\frac{\sigma}{4\pi}F^i{}_{am}F^i{}_b{}^m + s\sigma\,g_{ab}\, *L_{\rm YM}} \section{Geodesics} The geodesic equation \object{Geodesic Equation GEOq\^m}{ \frac{d^2x^\mu}{dt^2}+\{^\mu_{\pi\tau}\} \frac{dx^\pi}{dt}\frac{dx^\tau}{dt}=0} Here the parameter $ \end_inset t \begin_inset Formula $ must be declared by the \seethis{See page \pageref{affpar}.} \cmdind{Affine Parameter} {\tt Affine parameter} declaration. \section{Null Congruence and Optical Scalars} Let us consider the congruence defined by the vector field $ \end_inset k \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash alpha \end_layout \end_inset \begin_inset Formula $ \object{Congruence KV}{k=k^\mu\partial_\mu} This congruence is null iff \object{Null Congruence Condition NCo}{k\cdot k=0} holds. The congruence is geodesic iff the condition \object{Geodesics Congruence Condition GCo'a}{k^\mu\rim{\nabla}_\mu k^a=0} is fulfilled. For the null geodesic congruence one can calculate the {\tt Optical scalars} \object{Congruence Expansion thetaO}{\theta= \frac{1}{2}\rim{\nabla}{}^\pi k_\pi} \object{Congruence Squared Rotation omegaSQO}{\omega^2= \frac{1}{2}(\rim{\nabla}_{[\alpha}k_{\beta]})^2} \object{Congruence Squared Shear sigmaSQO}{\sigma\overline\sigma= \frac{1}{2}\left[ (\rim{\nabla}_{(\alpha}k_{\beta)})^2 -2\theta^2\right]} \section{Timelike Congruences and Kinematics} Let us consider the congruence determined by the velocity vector $ \end_inset u \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash alpha \end_layout \end_inset \begin_inset Formula $ \object{Velocity UU'a}{u^a} \object{Velocity Vector UV}{u=u^a\partial_a} The velocity vector must be normalized and the quantity \object{Velocity Square USQ}{u^2=u\cdot u} must be constant but nonzero. If the frame metric coincides with its default diagonal value \seethis{See \pref{defaultmetric}.} $ \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset = \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset diag \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset (-1,…) \begin_inset Formula $ then {\tt By default} we have for the velocity \begin{equation} u^a=(1,0,\dots,0) \end{equation} which means that the congruence is comoving in the given frame. In general case the velocity can be obtained {\tt From velocity vector} \begin{equation} u^a=u\ipr \theta^a \end{equation} We introduce the auxiliary object \object{Projector PR'a.b}{P^a{}_b= \delta^a_b-\frac{1}{u^2}u^an_b} The following four quantities called {\tt Kinematics} comprise the complete set of the congruence characteristics \object{Acceleration accU'a}{A^a=\rim{\nabla}_uu^a} \object{Vorticity omegaU.a.b}{\omega_{ab}= P^m{}_aP^n{}_b \rim{\nabla}_{[m}u_{n]}} \object{Volume Expansion thetaU}{\Theta=\rim{\nabla}_au^a} \object{Shear sigmaU.a.b}{ P^m{}_aP^n{}_b \rim{\nabla}_{(m}u_{n)}- \frac{1}{(d-1)}P_{ab}\Theta} \section{Ideal And Spin Fluid} The ideal fluid is characterized by the \object{Pressure PRES}{p} and \object{Energy Density ENER}{\varepsilon} The ideal fluid energy-momentum tensor is \begin{eqnarray} &&\mbox{\tt Ideal Fluid Energy-Momentum Tensor TIFL.a.b}= T^{\rm IF}_{ab} = \nonumber\\ &&\qquad\qquad=(\varepsilon+p)u_a u_b - u^2p g_{ab} \end{eqnarray} The rest of the section requires the nonmetricity be zero (\comm{NONMETR} is off). In addition spin-fluid is characterized by \object{Spin Density SPFLT.a.b }{S^{\rm SF}_{ab}=S^{\rm SF}_{[ab]}} or equivalently by \object{Spin Density 2-form SPFL }{S^{\rm SF}} The spin 2-form can be obtained {\tt From spin density} \begin{equation} S^{\rm SF}=\frac{1}{2}S^{\rm SF}_{ab} \theta^a\wedge\theta^a \end{equation} and $ \end_inset s \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is determined {\tt From spin density 2-form} \begin{equation} S^{\rm SF}_{ab}= \partial_b\ipr\partial_a\ipr S^{\rm SF} \end{equation} The spin density must satisfy the Frenkel condition \object{Frenkel Condition FCo}{u\ipr S^{\rm SF}=0} The spin fluid energy-momentum tensor is \begin{eqnarray} &&\mbox{\tt Spin Fluid Energy-Momentum Tensor TSFL.a.b}=T^{\rm SF}_{ab}= \nonumber\\ &&\qquad\qquad=(\varepsilon+p)u_a u_b - u^2p g_{ab}+\Delta_{(ab)} \end{eqnarray} where \begin{equation} \Delta_{ab}=-2(g^{cd}+u^{-2}\,u^cu^d) \nabla_c S^{\rm SF}_{(ab)d} \end{equation} \begin{equation} s^{\rm SF}_{abc}=u_a\,S^{\rm SF}_{bc} \end{equation} if torsion is zero (\comm{TORSION} off) and \begin{equation} \Delta_{ab}=2u^{-2}\,u_au^d\,\nabla_u S^{\rm SF}_{bd} \end{equation} if torsion is nonzero (\comm{TORSION} on). Notice that the energy-momentum \seethis{See \pref{tsym}.} tensor $ \end_inset T \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset SF \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is symmetrized. Finally yet another representation for the spin is the undotted spin 3-form \object{Undotted Fluid Spin 3-form SPFLU.AB }{s^{\rm SF}_{AB}} which is given by the standard spinor $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash tsst \end_layout \end_inset \begin_inset Formula $ tensor correspondence rules \begin{equation} s^{\rm SF}_{mab}\,*\theta^m \tsst \epsilon_{AB} s^{\rm SF}_{\dot A\dot B} + \epsilon_{\dot A\dot B}s^{\rm SF}_{AB} \end{equation} according to Eq. (\ref{asys}). \seethis{See \pref{asys}.} This quantity is used in the right-hand side of gravitational equations. \section{Total Energy-Momentum And Spin} \label{totalc} \enlargethispage{4mm} The total energy-momentum tensor \object{Total Energy-Momentum Tensor TENMOM.a.b}{T_{ab}} and the total undotted spin 3-form \seethis{See pages \pageref{graveq}\ and \pageref{metreq}.} \object{Total Undotted Spin 3-form SPINU.AB}{s_{AB}} play the role of sources in the right-hand side of the gravitational equations. The expression for these quantities read \begin{equation} T_{ab} = T^{\rm D}_{ab}+ T^{\rm EM}_{ab}+ T^{\rm YM}_{ab}+ T^{\rm Smin}_{ab}+ T^{\rm IF}_{ab}+ T^{\rm SF}_{ab} \label{b1} \end{equation} \begin{equation} s_{AB} = s_{AB}^{\rm D} + s_{AB}^{\rm SF} \label{b2} \end{equation} When $ \end_inset T \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset s \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ are calculated \grg\ does not tries to find value of all objects in the right-hand side of Eqs. (\ref{b1}), (\ref{b2}) instead it adds only the quantities whose value are currently defined. In particular if none of above tensors and spinors are defined then $ \end_inset T \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset =s \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset =0 \begin_inset Formula $. Notice that $ \end_inset T \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and all tensors in the right-hand side of Eq. (\ref{b1}) are symmetric. \seethis{See \pref{tsym}.} They are the symmetric parts of the canonical energy-momentum tensors. In addition we introduce the \object{Total Energy-Momentum Trace TENMOMT}{T=T^a{}_a} and the spinor \object{Total Energy-Momentum Spinor TENMOMS.AB.CD\cc}{T_{AB\dot C\dot D}} is a spinorial equivalent of the traceless part of $ \end_inset T \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ \begin{equation} T_{ab}-\frac{1}{4}g_{ab}T \tsst T_{AB\dot A\dot B} \end{equation} \section{Einstein Equations} The Einstein equation \object{Einstein Equation EEq.a.b} {R_{ab}-\frac{1}{2}g_{ab}R +\Lambda R =8\pi G\, T_{ab}} And the {\tt Spinor Einstein equations} \object{Traceless Einstein Equation CEEq.AB.CD\cc}{ C_{AB\dot C\dot D} = 8\pi G\, T_{AB\dot C\dot D}} \object{Trace of Einstein Equation TEEq} {R-4\Lambda = -8\pi G\, T} The cosmological constant is included in these equations iff the switch \comm{CCONST} is turned on \swind{CCONST} and its value is given by the constant \comm{CCONST}. The gravitational constant $ \end_inset G \begin_inset Formula $ is given by the constant \comm{GCONST}. \section{Gravitational Equations in Space With Torsion} Equations in this section are valid in dimension $ \end_inset d=4 \begin_inset Formula $ with the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ only. The $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset =1 \begin_inset Formula $ for the first signature and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset =-1 \begin_inset Formula $ for the second. The nonmetricity must be zero and the switch \comm{NONMETR} turned off. Let us consider the action \begin{equation} S=\int\left[\frac{\sigma}{16\pi G}L_{\rm g} +L_{\rm m}\right] \end{equation} where \object{Action LACT}{L_{\rm g}=\upsilon\,{\cal L}_{\rm g}} is the gravitational action 4-form and \begin{equation} L_{\rm m} = \upsilon\,{\cal L}_{\rm m} \end{equation} is the matter action 4-form. Let us define the following variational derivatives \begin{equation} Z^\mu{}_{a} = \frac{1}{\sqrt{-g}} \frac{\delta\sqrt{-g}{\cal L}_{\rm g}}{\delta h^a_\mu} ,\qquad t^\mu{}_{a} = \frac{\sigma}{\sqrt{-g}} \frac{\delta\sqrt{-g}{\cal L}_{\rm m}}{\delta h^a_\mu} \end{equation} \begin{equation} V^\mu{}_{ab} = \frac{1}{\sqrt{-g}} \frac{\delta\sqrt{-g}{\cal L}_{\rm g}}{\delta \omega^{ab}{}_\mu} ,\qquad s^\mu{}_{ab} = \frac{\sigma}{\sqrt{-g}} \frac{\delta\sqrt{-g}{\cal L}_{\rm m}}{\delta \omega^{ab}{}_\mu} \end{equation} Then the gravitational equations reads \begin{eqnarray} Z^\mu{}_a &=& -16\pi G\,t^\mu{}_a \label{zma} \\[2mm] V^\mu{}_{ab} &=& -16\pi G\,s^\mu{}_{ab} \label{vab} \end{eqnarray} Here the first equation is an analog of Einstein equation and has the canonical nonsymmetric energy-momentum tensor $ \end_inset t \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mu \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset Formula $ as a source. The source in the second equation is the spin tensor $ \end_inset s \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash mu \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. Now we rewrite these equation in other equivalent form. First let us define the following 3-forms \begin{equation} Z_a = Z^m{}_a\,*\theta_m,\qquad t_a = t^m{}_a\,*\theta_m \end{equation} \begin{equation} V_{ab} = V^m{}_{ab}\,*\theta_m,\qquad s_{ab} = s^m{}_{ab}\,*\theta_m \end{equation} Notice that Eq. (\ref{zma}) is not symmetric but \label{tsym} the antisymmetric part of this equation is expressed via second Eq. (\ref{vab}) due to Bianchi identity. Therefore only the symmetric part of Eq. (\ref{zma}) is essential. Eq. (\ref{vab}) is antisymmetric and we can consider its spinorial analog using the standard relations \begin{eqnarray} V_{ab} &\tsst& V_{A\dot AB\dot B}= \epsilon_{AB} V_{\dot A\dot B} + \epsilon_{\dot A\dot B}V_{AB} \\ s_{ab} &\tsst& s_{A\dot AB\dot B}= \epsilon_{AB} s_{\dot A\dot B} + \epsilon_{\dot A\dot B}s_{AB} \end{eqnarray} \seethis{See \pref{asys}.} Finally we define the {\tt Gravitational equations} in the form \label{graveq} \object{Metric Equation METRq.a.b}{-\frac12Z_{(ab)}=8\pi G\,T_{ab}} \object{Torsion Equation TORSq.AB}{V_{AB}=-16\pi G\,s_{AB}} where the currents in the right-hand side of equations are \seethis{See \pref{totalc}.} \object{Total Energy-Momentum Tensor TENMOM.a.b}{T_{ab}=t_{(ab)}} \object{Total Undotted Spin 3-form SPINU.AB}{s_{AB}} Now let us consider the equations which are used in \grg\ to compute the left-hand side of the gravitational equations $ \end_inset Z \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset (ab) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset V \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. We have to emphasize that we use \seethis{See \pref{spinors}.} spinors and all restrictions imposed by the spinorial formalism must be fulfilled. We consider the Lagrangian which is an arbitrary algebraic function of the curvature and torsion tensors \begin{equation} {\cal L}_{\rm g} = {\cal L}_{\rm g}(R_{abcd},Q_{abc}) \end{equation} No derivatives of the torsion or curvature are permitted. For such a Lagrangian we define so called curvature and torsion momentums \begin{equation} \widetilde{R}{}^{abcd} = 2\frac{\partial{\cal L}_{\rm g}(R,Q)}{\partial R_{abcd}},\qquad \widetilde{Q}{}^{abc} = 2\frac{\partial{\cal L}_{\rm g}(R,Q)}{\partial Q_{abc}},\qquad \end{equation} The corresponding objects are \object{Undotted Curvature Momentum POMEGAU.AB}{\widetilde{\Omega}_{AB}} \object{Torsion Momentum PTHETA'a}{\widetilde{\Theta}{}^a} where \begin{eqnarray} \widetilde{\Omega}_{ab} &=& \frac12 \widetilde{R}_{abcd}\,S^{cd} \\[1mm] \widetilde{\Theta}{}^a &=& \frac12 \widetilde{Q}{}^a{}_{cd}\,S^{cd} \end{eqnarray} and \begin{equation} \widetilde{\Omega}_{ab} \tsst \widetilde{\Omega}_{A\dot AB\dot B}= \epsilon_{AB} \widetilde{\Omega}_{\dot A\dot B} + \epsilon_{\dot A\dot B}\widetilde{\Omega}_{AB} \end{equation} If value of three objects $ \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ ({\tt Action}), $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ ({\tt Undotted curvature momentum}) and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Theta \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset Formula $ are specified then the {\tt Gravitational equations} can be calculated using equations ({\tt Standard way}) \begin{eqnarray} Z_{(ab)} &=& *(\theta_{(a}\wedge Z_{b)}),\nonumber\\[1mm] Z_a &=& D\widetilde{\Theta}_a + (\partial_a\ipr\Theta^b)\wedge\widetilde{\Theta}_b +2(\partial_a\ipr\Omega^{MN})\wedge\widetilde{\Omega}_{MN} \nonumber\\ && + {\rm c.c.}-\partial_a L_{\rm g} \end{eqnarray} \begin{eqnarray} &&V_{AB} = -D\widetilde{\Omega}_{AB} - \widetilde{\Theta}_{AB},\nonumber\\[1mm] && \theta_{[a}\wedge\widetilde{\Theta}_{b]} \tsst \epsilon_{AB} \widetilde{\Theta}_{\dot A\dot B} + \epsilon_{\dot A\dot B}\widetilde{\Theta}_{AB} \end{eqnarray} Since gravitational equations are computed in the spinorial formalism with the standard null frame \seethis{See pages \pageref{spinors}\ and \pageref{spinors1}.} the metric equation is complex and components $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 02 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 12 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 22 \begin_inset Formula $ are conjugated to $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 03 \begin_inset Formula $. $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 13 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 33 \begin_inset Formula $. Since these components are not independent For the sake of efficiency by default \grg\ computes only the $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 00 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 01 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 02 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 11 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 12 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 22 \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 23 \begin_inset Formula $ components of $ \end_inset Z \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset (ab) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ only. If you want to have all components the switch \comm{FULL} must be turned on. \swind{FULL} These equations allows one to compute field equations for gravity theory with an arbitrary Lagrangian. But the value of three quantities $ \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Theta \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset Formula $ must be specified by the user. In addition \grg\ has built-in formulas for the most general quadratic in torsion and curvature Lagrangian. The {\tt Standard way} for $ \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Theta \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout {} \end_layout \end_inset a \begin_inset Formula $ is \label{thetau} \begin{eqnarray} \widetilde{\Theta}{}^a &=& i\mu_1 (\stackrel{\scriptscriptstyle\rm c}{\vartheta}{}^a -{\rm c.c.}) +i\mu_2 (\stackrel{\scriptscriptstyle\rm t}{\vartheta}{}^a -{\rm c.c.}) +i\mu_3 (\stackrel{\scriptscriptstyle\rm a}{\vartheta}\!{}^a -{\rm c.c.}), \\[2mm] \widetilde{\Omega}_{AB} &=& i(\lambda_0-\sigma\,8\pi G\, a_0\phi^2)\, S_{AB} \nonumber\\&& +i\lambda_1 \OO{w}_{AB} -i\lambda_2 \OO{c}_{AB} +i\lambda_3 \OO{r}_{AB} \nonumber\\&& +i\lambda_4 \OO{a}_{AB} -i\lambda_5 \OO{b}_{AB} +i\lambda_6 \OO{d}_{AB} , \\[2mm] L_{\rm g} &=& (-2\Lambda +\frac{1}{2}\lambda_0R -\sigma\,4\pi G a_0 \phi^2 R) \upsilon + \Omega^{AB}\wedge\widetilde{\Omega}_{AB} + {\rm c.c.} \nonumber\\&& + \frac{1}{2} \Theta^a\wedge\widetilde{\Theta}_a \end{eqnarray} The cosmological term $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Lambda \end_layout \end_inset \begin_inset Formula $ is included into equations iff the switch \comm{CCONST} is turned on \swinda{CCONST} and the value of $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Lambda \end_layout \end_inset \begin_inset Formula $ is given by the constant \comm{CCONST}. The term with the scalar field $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash phi \end_layout \end_inset \begin_inset Formula $ is included into equations iff the switch \comm{NONMIN} is on. \swinda{NONMIN} The gravitational constant $ \end_inset G \begin_inset Formula $ is given by the constant \comm{GCONST}. The parameters of the quadratic Lagrangian are given by the objects \object{L-Constants LCONST.i6}{\lambda_i} \object{M-Constants MCONST.i3}{\mu_i} \object{A-Constants ACONST.i2}{a_i} The default value of these objects ({\tt Standard way}) is \begin{eqnarray} \lambda_i &=& (\mbox{\tt LC0},\mbox{\tt LC1},\mbox{\tt LC2},\mbox{\tt LC3},\mbox{\tt LC4},\mbox{\tt LC5},\mbox{\tt LC6}), \\ \mu_i &=& (0,\mbox{\tt MC1},\mbox{\tt MC2},\mbox{\tt MC32}), \\ a_i &=& (\mbox{\tt AC0},0,0) \end{eqnarray} \section{Gravitational Equations in Riemann Space} Equations in this section are valid in dimension $ \end_inset d=4 \begin_inset Formula $ with the signature $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (-,+,+,+) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset (+,-,-,-) \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ only. The $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset =1 \begin_inset Formula $ for the first signature and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash sigma \end_layout \end_inset =-1 \begin_inset Formula $ for the second. The nonmetricity and torsion must be zero and the switches \comm{NONMETR} and \comm{TORSION} must be turned off. Let us consider the action \begin{equation} S=\int\left[\frac{\sigma}{16\pi G}L_{\rm g} +L_{\rm m}\right] \end{equation} where \object{Action LACT}{L_{\rm g}=\upsilon\,{\cal L}_{\rm g}} is the gravitational action 4-form and \begin{equation} L_{\rm m} = \upsilon\,{\cal L}_{\rm m} \end{equation} is the matter action 4-form. Let us define the following variational derivatives \begin{equation} Z^\mu{}_{a} = \frac{1}{\sqrt{-g}} \frac{\delta\sqrt{-g}{\cal L}_{\rm g}}{\delta h^a_\mu} ,\qquad T^\mu{}_{a} = \frac{\sigma}{\sqrt{-g}} \frac{\delta\sqrt{-g}{\cal L}_{\rm m}}{\delta h^a_\mu} \end{equation} Then the {\tt Metric equation} is \label{metreq} \object{Metric Equation METRq.a.b}{-\frac12Z_{ab}=8\pi G\,T_{ab}} Notice that $ \end_inset Z \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset T \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ are automatically symmetric. Let us define 3-form \begin{equation} Z_a = Z^m{}_a\,*\theta_m,\qquad t_a = t^m{}_a\,*\theta_m \end{equation} Now we consider the equations which are used in \grg\ to compute the left-hand side of the metric equation $ \end_inset Z \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset ab \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $. We have to emphasize that we use spinors and all restrictions imposed by the spinorial formalism \seethis{See pages \pageref{spinors}\ or \pageref{spinors1}.} must be fulfilled. We consider the Lagrangian which is an arbitrary algebraic function of the curvature tensor \begin{equation} {\cal L}_{\rm g} = {\cal L}_{\rm g}(R_{abcd}) \end{equation} No derivatives of the curvature are permitted. For such a Lagrangian we define so called curvature momentum \begin{equation} \widetilde{R}{}^{abcd} = 2\frac{\partial{\cal L}_{\rm g}(R)}{\partial R_{abcd}} \end{equation} The corresponding \grg\ built-in object is \object{Undotted Curvature Momentum POMEGAU.AB}{\widetilde{\Omega}_{AB}} where \begin{eqnarray} \widetilde{\Omega}_{ab} &=& \frac12 \widetilde{R}_{abcd}\,S^{cd} \\[1mm] \end{eqnarray} and \begin{equation} \widetilde{\Omega}_{ab} \tsst \widetilde{\Omega}_{A\dot AB\dot B}= \epsilon_{AB} \widetilde{\Omega}_{\dot A\dot B} + \epsilon_{\dot A\dot B}\widetilde{\Omega}_{AB} \end{equation} If value of the objects $ \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ ({\tt Action}) and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ ({\tt Undotted curvature momentum}) is specified then the {\tt Metric equation} can be calculated using equations ({\tt Standard way}) \begin{eqnarray} Z_{ab} &=& *(\theta_{(a}\wedge Z_{b)}),\nonumber\\[1mm] Z_a &=& D [ 2\partial_m\ipr D\widetilde{\Omega}_a{}^{m} -{\frac{1}{2}}\theta_a\!\wedge (\partial_m\ipr\partial_n\ipr D\widetilde{\Omega}{}^{mn})] \nonumber\\&& +2(\partial_a\ipr\Omega^{MN})\wedge\widetilde{\Omega}_{MN} + {\rm c.c.}-\partial_a L_{\rm g} \end{eqnarray} Since gravitational equations are computed in the spinorial formalism with the standard null frame \seethis{See \pref{spinors}\ or \pref{spinors1}.} the metric equation is complex and components $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 02 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 12 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 22 \begin_inset Formula $ are conjugated to $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 03 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 13 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 33 \begin_inset Formula $. For the sake of efficiency by default \grg\ computes only the components $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 00 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 01 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 02 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 11 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 12 \begin_inset Formula $, $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 22 \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash scriptstyle \end_layout \end_inset 23 \begin_inset Formula $ only. If you want to have all components the switch \comm{FULL} must be turned on. \swinda{FULL} These equations allows one to compute field equations for gravity theory with an arbitrary Lagrangian. But the value of three quantities $ \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ must be specified by user. In addition \grg\ has built-in formulas for the most general quadratic in the curvature Lagrangian. The {\tt Standard way} for $ \end_inset L \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash rm \end_layout \end_inset g \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ and $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash widetilde \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Omega \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout { \end_layout \end_inset AB \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset Formula $ is \begin{eqnarray} \widetilde{\Omega}_{AB} &=& i(\lambda_0-\sigma8\pi G\, a_0\phi^2)\, S_{AB} \nonumber\\&& +i\lambda_1 \OO{w}_{AB} -i\lambda_2 \OO{c}_{AB} +i\lambda_3 \OO{r}_{AB}, \\[2mm] L_{\rm g} &=& (-2\Lambda +{\frac{1}{2}}\lambda_0R -\sigma4\pi G a_0 \phi^2 R) \upsilon + \Omega^{AB}\wedge\widetilde{\Omega}_{AB} + {\rm c.c.} \end{eqnarray} The cosmological term is included into equations iff the switch \comm{CCONST} is on \swinda{CCONST} and the value of $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash Lambda \end_layout \end_inset \begin_inset Formula $ is given by the constant \comm{CCONST}. The term with the scalar field $ \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash phi \end_layout \end_inset \begin_inset Formula $ is included into equations iff the switch \comm{NONMIN} is on. \swinda{NONMIN} The gravitational constant $ \end_inset G \begin_inset Formula $ is given by the constant \comm{GCONST}. The parameters of the quadratic lagrangian are given by the object \object{L-Constants LCONST.i6}{\lambda_i} \object{A-Constants ACONST.i2}{a_i} The default value of these objects ({\tt Standard way}) is \begin{eqnarray} \lambda_i &=& (\mbox{\tt LC0},\mbox{\tt LC1},\mbox{\tt LC2},\mbox{\tt LC3},\mbox{\tt LC4},\mbox{\tt LC5},\mbox{\tt LC6}), \\ a_i &=& (\mbox{\tt AC0},0,0) \end{eqnarray} \appendix \chapter{\grg\ Switches}\vspace*{-6mm} \index{Switches} \tabcolsep=1.5mm \begin{tabular}{|c|c|l|c|} \hline Switch & Default &\qquad Description & See \\ & State & & page\\ \hline \tt AEVAL & Off & Use {\tt AEVAL} instead of {\tt REVAL}. &\pageref{AEVAL}\\ \tt WRS & On & Re-simplify object before printing. &\pageref{WRS}\\ \tt WMATR & Off & Write 2-index objects in matrix form. &\pageref{WMATR}\\ \tt TORSION & Off & Torsion. &\pageref{TORSION}\\ \tt NONMETR & Off & Nonmetricity. &\pageref{NONMETR}\\ \tt UNLCORD & On & Save coordinates in {\tt Unload}. &\pageref{UNLCORD}\\ \tt AUTO & On & Automatic object calculation in expressions. &\pageref{AUTO}\\ \tt TRACE & On & Trace the calculation process. &\pageref{TRACE}\\ \tt SHOWCOMMANDS & Off & Show compound command expansion. &\pageref{SHOWCOMMANDS}\\ \tt EXPANDSYM & Off & Enable {\tt Sy Asy Cy} in expressions &\pageref{EXPANDSYM}\\ \tt DFPCOMMUTE & On & Commutativity of {\tt DFP} derivatives. &\pageref{DFPCOMMUTE}\\ \tt NONMIN & Off & Nonminimal interaction for scalar field. &\pageref{NONMIN}\\ \tt NOFREEVARS & Off & Prohibit free variables in {\tt Print}. &\pageref{NOFREEVARS}\\ \tt CCONST & Off & Include cosmological constant in equations. &\pageref{CCONST}\\ \tt FULL & Off & Number of components in {\tt Metric Equation}. &\pageref{FULL}\\ \tt LATEX & Off & \LaTeX\ output mode. &\pageref{LATEX}\\ \tt GRG & Off & \grg\ output mode. &\pageref{GRG}\\ \tt REDUCE & Off & \reduce\ output mode. &\pageref{REDUCE}\\ \tt MAPLE & Off & {\sc Maple} output mode. &\pageref{MAPLE}\\ \tt MATH & Off & {\sc Mathematica} output mode. &\pageref{MATH}\\ \tt MACSYMA & Off & {\sc Macsyma} output mode. &\pageref{MACSYMA}\\ \tt DFINDEXED & Off & Print {\tt DF} in index notation. &\pageref{DFINDEXED}\\ \tt BATCH & Off & Batch mode. &\pageref{BATCH}\\ \tt HOLONOMIC & On & Keep frame holonomic. &\pageref{HOLONOMIC}\\ \tt SHOWEXPR & Off & Print expressions during algebraic &\pageref{SHOWEXPR}\\ \tt & & classification. &\\ \hline \end{tabular} \chapter{Macro Objects} \index{Macro Objects} Macro objects can be used in expression, in {\tt Write} and {\tt Show} commands but not in the {\tt Find} command. The notation for indices is the same as in the {\tt New Object} declaration (see page \pageref{indices}). \begin{center} \section{Dimension and Signature} \begin{tabular}{|l|l|} \hline \tt dim & Dimension $d$ \\ \hline \tt sdiag.idim & {\tt sdiag(\parm{n})} is the $n$'th element of the \\ & signature diag($-1,+1$\dots) \\ \hline \tt sign & Product of the signature specification \\ \tt sgnt & elements $\prod_{n=0}^{d-1}\mbox{\tt sdiag(}n\mbox{\tt)}$ \\[1mm] \hline \tt mpsgn & {\tt sdiag(0)} \\ \tt pmsgn & {\tt -sdiag(0)} \\ \hline \end{tabular} \section{Metric and Frame} \begin{tabular}{|l|l|} \hline \tt x\^m & $m$'th coordinate \\ \tt X\^m & \\ \hline \tt h'a\_m & Frame coefficients \\ \tt hi.a\^m & \\ \hline \tt g\_m\_n & Holonomic metric \\ \tt gi\^m\^n & \\ \hline \end{tabular} \section{Delta and Epsilon Symbols} \begin{tabular}{|l|l|} \hline \tt del'a.b & Delta symbols \\ \tt delh\^m\_n & \\ \hline \tt eps.a.b.c.d & Totally antisymmetric symbols \\ \tt epsi'a'b'c'd & (number of indices depend on $d$) \\ \tt epsh\_m\_n\_p\_q & \\ \tt epsih\^m\^n\^p\^q & \\ \hline \end{tabular} \section{Spinors} \begin{tabular}{|l|l|} \hline \tt DEL'A.B & Delta symbol \\ \hline \tt EPS.A.B & Spinorial metric \\ \tt EPSI'A'B & \\ \hline \tt sigma'a.A.B\cc & Sigma matrices \\ \tt sigmai.a'A'B\cc & \\ \hline \tt cci.i3 & Frame index conjugation in standard null frame \\ & {\tt cci(0)=0}\ {\tt cci(1)=1}\ {\tt cci(2)=3}\ {\tt cci(3)=2} \\ \hline \end{tabular} \section{Connection Coefficients} \begin{tabular}{|l|l|} \hline \tt CHR\^m\_n\_p & Christoffel symbols $\{{}^\mu_{\nu\pi}\}$ \\ \tt CHRF\_m\_n\_p & and $[{}_{\mu},_{\nu\pi}]$ \\ \tt CHRT\_m & Christoffel symbol trace $\{{}^\pi_{\pi\mu}\}$ \\ \hline \tt SPCOEF.AB.c & Spin coefficients $\omega_{AB\,c}$ \\ \hline \end{tabular} \section{NP Formalism} \begin{tabular}{|l|c|} \hline \tt PHINP.AB.CD~ & $\Phi_{AB\dot{c}\dot{D}}$ \\ \tt PSINP.ABCD & $\Psi_{ABCD}$ \\ \hline \tt alphanp & $\alpha$ \\ \tt betanp & $\beta$ \\ \tt gammanp & $\gamma$ \\ \tt epsilonnp & $\epsilon$ \\ \tt kappanp & $\kappa$ \\ \tt rhonp & $\rho$ \\ \tt sigmanp & $\sigma$ \\ \tt taunp & $\tau$ \\ \tt munp & $\mu$ \\ \tt nunp & $\nu$ \\ \tt lambdanp & $\lambda$ \\ \tt pinp & $\pi$ \\ \hline \tt DD & $D$ \\ \tt DT & $\Delta$ \\ \tt du & $\delta$ \\ \tt dd & $\overline\delta$ \\ \hline \end{tabular} \end{center} \chapter{Objects} Here we present the complete list of built-in objects with names and identifiers. The notation for indices is the same as in the {\tt New Object} declaration (see page \pageref{indices}). Some names (group names) refer to a set of objects. For example the group name {\tt Spinorial S - forms} below denotes {\tt SU.AB} and {\tt SD.AB\cc} \begin{center} \section{Metric, Frame, Basis, Volume \dots} \begin{tabular}{|l|l|}\hline \tt Frame &\tt T'a\\ \tt Vector Frame &\tt D.a\\ \hline \tt Metric &\tt G.a.b\\ \tt Inverse Metric &\tt GI'a'b\\ \tt Det of Metric &\tt detG\\ \tt Det of Holonomic Metric &\tt detg\\ \tt Sqrt Det of Metric &\tt sdetG\\ \hline \tt Volume &\tt VOL\\ \hline \tt Basis &\tt b'idim \\ \tt Vector Basis &\tt e.idim \\ \hline \tt S-forms &\tt S'a'b\\ \hline \multicolumn{2}{|c|}{\tt Spinorial S-forms} \\ \tt Undotted S-forms &\tt SU.AB\\ \tt Dotted S-forms &\tt SD.AB\cc\\ \hline\end{tabular} \section{Rotation Matrices} \begin{tabular}{|l|l|}\hline \tt Frame Transformation &\tt L'a.b \\ \tt Spinorial Transformation &\tt LS.A'B \\ \hline\end{tabular} \section{Connection and related objects} \begin{tabular}{|l|l|}\hline \tt Frame Connection &\tt omega'a.b\\ \tt Holonomic Connection &\tt GAMMA\^m\_n\\ \hline \multicolumn{2}{|c|}{\tt Spinorial Connection}\\ \tt Undotted Connection &\tt omegau.AB\\ \tt Dotted Connection &\tt omegad.AB\cc\\ \hline \tt Riemann Frame Connection &\tt romega'a.b\\ \tt Riemann Holonomic Connection &\tt RGAMMA\^m\_n\\ \hline \multicolumn{2}{|c|}{\tt Riemann Spinorial Connection}\\ \tt Riemann Undotted Connection &\tt romegau.AB\\ \tt Riemann Dotted Connection &\tt romegad.AB\cc\\ \hline \tt Connection Defect &\tt K'a.b\\ \hline\end{tabular} \section{Torsion} \begin{tabular}{|l|l|}\hline \tt Torsion &\tt THETA'a\\ \tt Contorsion &\tt KQ'a.b\\ \tt Torsion Trace 1-form &\tt QQ\\ \tt Antisymmetric Torsion 3-form &\tt QQA\\ \hline \multicolumn{2}{|c|}{\tt Spinorial Contorsion}\\ \tt Undotted Contorsion &\tt KU.AB\\ \tt Dotted Contorsion &\tt KD.AB\cc\\ \hline \multicolumn{2}{|c|}{\tt Torsion Spinors }\\ \multicolumn{2}{|c|}{\tt Torsion Components }\\ \tt Torsion Trace &\tt QT'a\\ \tt Torsion Pseudo Trace &\tt QP'a\\ \tt Traceless Torsion Spinor &\tt QC.ABC.D\cc\\ \hline \multicolumn{2}{|c|}{\tt Torsion 2-forms}\\ \tt Traceless Torsion 2-form &\tt THQC'a\\ \tt Torsion Trace 2-form &\tt THQT'a\\ \tt Antisymmetric Torsion 2-form &\tt THQA'a\\ \hline \multicolumn{2}{|c|}{\tt Undotted Torsion 2-forms}\\ \tt Undotted Torsion Trace 2-form &\tt THQTU'a\\ \tt Undotted Antisymmetric Torsion 2-form &\tt THQAU'a\\ \tt Undotted Traceless Torsion 2-form &\tt THQCU'a\\ \hline\end{tabular} \section{Curvature} \label{curspincoll} \begin{tabular}{|l|l|}\hline \tt Curvature &\tt OMEGA'a.b\\ \hline \multicolumn{2}{|c|}{\tt Spinorial Curvature}\\ \tt Undotted Curvature &\tt OMEGAU.AB\\ \tt Dotted Curvature &\tt OMEGAD.AB\cc\\ \hline \tt Riemann Tensor &\tt RIM'a.b.c.d\\ \tt Ricci Tensor &\tt RIC.a.b\\ \tt A-Ricci Tensor &\tt RICA.a.b\\ \tt S-Ricci Tensor &\tt RICS.a.b\\ \tt Homothetic Curvature &\tt OMEGAH\\ \tt Einstein Tensor &\tt GT.a.b\\ \hline \multicolumn{2}{|c|}{\tt Curvature Spinors}\\ \multicolumn{2}{|c|}{\tt Curvature Components}\\ \tt Weyl Spinor &\tt RW.ABCD\\ \tt Traceless Ricci Spinor &\tt RC.AB.CD\cc\\ \tt Scalar Curvature &\tt RR\\ \tt Ricanti Spinor &\tt RA.AB\\ \tt Traceless Deviation Spinor &\tt RB.AB.CD\cc\\ \tt Scalar Deviation &\tt RD\\ \hline \multicolumn{2}{|c|}{\tt Undotted Curvature 2-forms}\\ \tt Undotted Weyl 2-form &\tt OMWU.AB \\ \tt Undotted Traceless Ricci 2-form &\tt OMCU.AB \\ \tt Undotted Scalar Curvature 2-form &\tt OMRU.AB \\ \tt Undotted Ricanti 2-form &\tt OMAU.AB \\ \tt Undotted Traceless Deviation 2-form &\tt OMBU.AB \\ \tt Undotted Scalar Deviation 2-form &\tt OMDU.AB \\ \hline \multicolumn{2}{|c|}{\tt Curvature 2-forms}\\ \tt Weyl 2-form &\tt OMW.a.b \\ \tt Traceless Ricci 2-form &\tt OMC.a.b \\ \tt Scalar Curvature 2-form &\tt OMR.a.b \\ \tt Ricanti 2-form &\tt OMA.a.b \\ \tt Traceless Deviation 2-form &\tt OMB.a.b \\ \tt Antisymmetric Curvature 2-form &\tt OMD.a.b \\ \tt Homothetic Curvature 2-form &\tt OSH.a.b \\ \tt Antisymmetric S-Ricci 2-form &\tt OSA.a.b \\ \tt Traceless S-Ricci 2-form &\tt OSC.a.b \\ \tt Antisymmetric S-Curvature 2-form &\tt OSV.a.b \\ \tt Symmetric S-Curvature 2-form &\tt OSU.a.b \\ \hline \end{tabular} \section{Nonmetricity} \begin{tabular}{|l|l|}\hline \tt Nonmetricity &\tt N.a.b\\ \tt Nonmetricity Defect &\tt KN'a.b\\ \tt Weyl Vector &\tt NNW\\ \tt Nonmetricity Trace &\tt NNT\\ \hline \multicolumn{2}{|c|}{\tt Nonmetricity 1-forms}\\ \tt Symmetric Nonmetricity 1-form &\tt NC.a.b\\ \tt Antisymmetric Nonmetricity 1-form &\tt NA.a.b\\ \tt Nonmetricity Trace 1-form &\tt NT.a.b\\ \tt Weyl Nonmetricity 1-form &\tt NW.a.b\\ \hline\end{tabular} \section{EM field} \begin{tabular}{|l|l|}\hline \tt EM Potential &\tt A\\ \tt Current 1-form &\tt J\\ \tt EM Action &\tt EMACT\\ \tt EM 2-form &\tt FF\\ \tt EM Tensor &\tt FT.a.b\\ \hline \multicolumn{2}{|c|}{\tt Maxwell Equations}\\ \tt First Maxwell Equation &\tt MWFq\\ \tt Second Maxwell Equation &\tt MWSq\\ \hline \tt Continuity Equation &\tt COq\\ \tt EM Energy-Momentum Tensor &\tt TEM.a.b\\ \hline \multicolumn{2}{|c|}{\tt EM Scalars}\\ \tt First EM Scalar &\tt SCF\\ \tt Second EM Scalar &\tt SCS\\ \hline \tt Selfduality Equation &\tt SDq.AB\cc\\ \tt Complex EM 2-form &\tt FFU\\ \tt Complex Maxwell Equation &\tt MWUq\\ \tt Undotted EM Spinor &\tt FIU.AB\\ \tt Complex EM Scalar &\tt SCU\\ \tt EM Energy-Momentum Spinor &\tt TEMS.AB.CD\cc\\ \hline\end{tabular} \section{Scalar field} \begin{tabular}{|l|l|}\hline \tt Scalar Equation &\tt SCq\\ \tt Scalar Field &\tt FI\\ \tt Scalar Action &\tt SACT\\ \tt Minimal Scalar Action &\tt SACTMIN\\ \tt Minimal Scalar Energy-Momentum Tensor &\tt TSCLMIN.a.b\\ \hline\end{tabular} \section{YM field} \begin{tabular}{|l|l|}\hline \tt YM Potential &\tt AYM.i9\\ \tt Structural Constants &\tt SCONST.i9.j9.k9\\ \tt YM Action &\tt YMACT\\ \tt YM 2-form &\tt FFYM.i9\\ \tt YM Tensor &\tt FTYM.i9.a.b\\ \hline \multicolumn{2}{|c|}{\tt YM Equations}\\ \tt First YM Equation &\tt YMFq.i9\\ \tt Second YM Equation &\tt YMSq.i9\\ \hline \tt YM Energy-Momentum Tensor &\tt TYM.a.b\\ \hline\end{tabular} \section{Dirac field} \begin{tabular}{|l|l|}\hline \multicolumn{2}{|c|}{\tt Dirac Spinor}\\ \tt Phi Spinor &\tt PHI.A\\ \tt Chi Spinor &\tt CHI.B\\ \hline \tt Dirac Action 4-form &\tt DACT\\ \tt Undotted Dirac Spin 3-Form &\tt SPDIU.AB\\ \tt Dirac Energy-Momentum Tensor &\tt TDI.a.b\\ \hline \multicolumn{2}{|c|}{\tt Dirac Equation}\\ \tt Phi Dirac Equation &\tt DPq.A\cc\\ \tt Chi Dirac Equation &\tt DCq.A\cc\\ \hline\end{tabular} \section{Geodesics} \begin{tabular}{|l|l|}\hline \tt Geodesic Equation &\tt GEOq\^m\\ \hline\end{tabular} \section{Null Congruence} \begin{tabular}{|l|l|}\hline \tt Congruence &\tt KV\\ \tt Null Congruence Condition &\tt NCo\\ \tt Geodesics Congruence Condition&\tt GCo'a\\ \hline \multicolumn{2}{|c|}{\tt Optical Scalars}\\ \tt Congruence Expansion &\tt thetaO\\ \tt Congruence Squared Rotation &\tt omegaSQO\\ \tt Congruence Squared Shear &\tt sigmaSQO\\ \hline\end{tabular} \section{Kinematics} \begin{tabular}{|l|l|}\hline \tt Velocity Vector &\tt UV\\ \tt Velocity &\tt UU'a\\ \tt Velocity Square &\tt USQ\\ \tt Projector &\tt PR'a.b\\ \hline \multicolumn{2}{|c|}{\tt Kinematics}\\ \tt Acceleration &\tt accU'a\\ \tt Vorticity &\tt omegaU.a.b\\ \tt Volume Expansion &\tt thetaU\\ \tt Shear &\tt sigmaU.a.b\\ \hline\end{tabular} \section{Ideal and Spin Fluid} \begin{tabular}{|l|l|}\hline \tt Pressure &\tt PRES\\ \tt Energy Density &\tt ENER\\ \tt Ideal Fluid Energy-Momentum Tensor &\tt TIFL.a.b\\ \hline \tt Spin Fluid Energy-Momentum Tensor &\tt TSFL.a.b \\ \tt Spin Density &\tt SPFLT.a.b \\ \tt Spin Density 2-form &\tt SPFL \\ \tt Undotted Fluid Spin 3-form &\tt SPFLU.AB \\ \tt Frenkel Condition &\tt FCo \\ \hline\end{tabular} \section{Total Energy-Momentum and Spin} \begin{tabular}{|l|l|}\hline \tt Total Energy-Momentum Tensor &\tt TENMOM.a.b\\ \tt Total Energy-Momentum Spinor &\tt TENMOMS.AB.CD\cc\\ \tt Total Energy-Momentum Trace &\tt TENMOMT\\ \tt Total Undotted Spin 3-form &\tt SPINU.AB\\ \hline\end{tabular} \section{Einstein Equations} \begin{tabular}{|l|l|}\hline \tt Einstein Equation &\tt EEq.a.b\\ \hline \multicolumn{2}{|c|}{\tt Spinor Einstein Equations}\\ \tt Traceless Einstein Equation &\tt CEEq.AB.CD\cc\\ \tt Trace of Einstein Equation &\tt TEEq\\ \hline\end{tabular} \section{Constants} \begin{tabular}{|l|l|}\hline \tt A-Constants &\tt ACONST.i2\\ \tt L-Constants &\tt LCONST.i6\\ \tt M-Constants &\tt MCONST.i3\\ \hline\end{tabular} \section{Gravitational Equations} \begin{tabular}{|l|l|}\hline \tt Action &\tt LACT\\ \tt Undotted Curvature Momentum &\tt POMEGAU.AB\\ \tt Torsion Momentum &\tt PTHETA'a\\ \hline \multicolumn{2}{|c|}{\tt Gravitational Equations}\\ \tt Metric Equation &\tt METRq.a.b\\ \tt Torsion Equation &\tt TORSq.AB\\ \hline\end{tabular} \end{center} \chapter{Standard Synonymy} \index{Synonymy} Below we present the default synonymy as it is defined in the global configuration file. See section \ref{tuning} to find out how to change the default synonymy or define a new one. \begin{verbatim} Affine Aff Anholonomic Nonholonomic AMode ABasis Antisymmetric Asy Change Transform Classify Class Components Comp Connection Con Constants Const Constant Coordinates Cord Curvature Cur Dimension Dim Dotted Do Equation Equations Eq Erase Delete Del Evaluate Eval Simplify Find F Calculate Calc Form Forms Functions Fun Function Generic Gen Gravitational Gravity Gravitation Grav Holonomic HMode HBasis Inverse Inv Load Restore Next N Normalize Normal Object Obj Output Out Parameter Par Rotation Rot Scalar Scal Show ? Signature Sig Solutions Solution Sol Spinor Spin Spinorial Sp standardlisp lisp Switch Sw Symmetries Sym Symmetric Tensor Tensors Tens Torsion Tors Transformation Trans Undotted Un Unload Save Vector Vec Write W Zero Nullify \end{verbatim} \makeatletter \if@openright\cleardoublepage\else\clearpage\fi \makeatother \thispagestyle{empty} \def\indexname{INDEX} \printindex {document} %======== End of grg32.tex ==============================================% $ \end_inset \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Standard \family typewriter \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \begin_inset ERT status collapsed \begin_layout Plain Layout } \end_layout \end_inset \end_layout \end_body \end_document