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%%% %%% The tree structure for the information browser is %%% given by the \section, \subsection, \subsubsection commands %%% \section{System interaction} %%% %%% Environments like Switch serve a triple purpose: %%% - the node is defined %%% - an index entry "demo switch" is generated %%% - a cross reference with symbolic name "switch:demo" is generated. %%% This can be used used the \ref, \pageref, \nameref, %%% and \see commands. %%% Additional \index entries or cross reference keys can be generated %%% with the \index and \label commands. %%% \begin{Switch}{demo} The \name{demo} switch is used for interactive files, causing the system to pause after each command in the file until you type a \key{Return}. Default is \name{off}. %%% %%% The parts of a node are given as environments. Defined are: %%% Comments, Examples, Related %%% \begin{Comments} The switch \name{demo} has no effect on top level interactive statements. Use it when you want to slow down operations in a file so you can see what is happening. You can either include the \name{on demo} command in the file, or enter it from the top level before bringing in any file. Unlike the \name{pause} command, \name{on demo} does not permit you to interrupt the file for questions of your own. \end{Comments} %%% %%% The Related environment points to related information. It should %%% also use a cross ref, but that is not yet implemented %%% \begin{Related} \item [\name{in} command] Reading from files. \item [\name{echo} switch] Seeing what is read in. \end{Related} \end{Switch} \section{Polynomials} \subsection{Polynomial operators} \begin{Operator}{den} The {den} operator returns the denominator of its argument. %%% %%% The syntax description needs perhaps a bit more work. %%% \name and \arg are purely for printing (i.e. selecting a different %%% typeface %%% \begin{Syntax} \name{den}\(\arg{expression}\) \end{Syntax} \arg{expression} is ordinarily a rational expression, but may be any valid scalar \REDUCE\ expression. \begin{Examples} a := x**3 + 3*x**2 + 12*x; & A := X*(X^2 + 3*X + 12) \\ b := 4*x*y + x*sin(x); & B := X*(SIN(X) + 4*Y) \\ den(a/b); & SIN(X) + 4*Y \\ den(a/4 + b/5); & 20 \\ den(100/6); & 3 \\ den(sin(x)); & 1 \\ for i := 1:3 sum part(firstlis,i)*part(secondlis,i); & A*X + B*Y + C*Z \end{Examples} \end{Operator} \begin{Comments} \name{den} returns the denominator of the expression after it has been simplified by \REDUCE. As seen in the examples, this includes putting sums of rational expressions over a common denominator, and reducing common factors where possible. If the expression does not have any other denominator, $1$ is returned. Switch settings, such as \name{mcd} or \name{rational}, have an effect on the denominator of an expression. \end{Comments} \subsection{Dependency information} \begin{Declaration}{depend} \name{depend} declares that its first argument depends on the rest of its arguments. \begin{Syntax} \name{depend} \arg{kernel}\{,\arg{kernel}\}\repeated \end{Syntax} \arg{kernel} must be a legal variable name or a prefix operator \see{kernel}). \begin{Examples} depend y,x; \\ df(y**2,x); & 2*DF(Y,X)*Y \\ depend z,cos(x),y; \\ df(sin(z),cos(x)); & COS(Z)*DF(Z,COS(X)) \\ df(z**2,x); & 2*DF(Z,X)*Z \\ nodepend z,y; \\ df(z**2,x); & 2*DF(Z,X)*Z \\ cc := df(y**2,x); & CC := 2*DF(Y,x)*Y \\ y := tan x; & Y := TAN(X) \\ cc; & 2*TAN(X)*(TAN(X)^{2} + 1) \end{Examples} \begin{Comments} Dependencies can be removed by using the declaration \nameref{nodepend}. The differentiation opeartor uses this information, as shown in the examples above. Linear operators alos use knowledge of dependencies (see \nameref{linear}). Note that dependencies can be nested: Having declared $y$ to depend on $x$, and $z$ to depend on $y$, we see that the chain rule was applied to the derivative of a function of $z$ wiht respect to $x$. If the explicit function of the dependencyis later entered into the system, terms with \name{DF(Y,X)}, for example, are expanded when they are displayed again, as shown in the last example. \end{Comments} \end{Declaration} \section{The Taylor package} \begin{Operator}{taylor} The \name{taylor} operator is used for expansion in power series\index{series}. \begin{Syntax} \name{taylor}\(\arg{expression},% \{\arg{kernel},\arg{expression},\arg{integer}\}% \repeated\) \end{Syntax} This returns the expansion of the first argument with respect to \arg{kernel} about \arg{expression} to order \arg{integer}. \begin{Examples} taylor(e^(x^2+y^2),x,0,2,y,0,2); & 1 + Y^2 + X^2 + Y^2*X^2 + O(X^{3},Y^{3})\\ taylor(log(1+x),x,0,2); & X - \rfrac{1}{2}*X^{2} + O(X^{3}) \end{Examples} \begin{Comments} The expansion is performed variable per variable, i.e.\ in the example above by first expanding $\exp(x^{2}+y^{2})$ with respect to $x$ and then expanding every coefficient with respect to $y$. If the switch \nameref{taylorkeeporiginal} is set to \name{on} the original expression is kept for later reference. Printing is controlled by the variable \nameref{taylorprintterms}. \end{Comments} \begin{Related} \item[tps] Truncated Power Series. \item[Koepff] Complete power series \end{Related} \end{Operator} \subsection{Controlling the package} \begin{Switch}{taylorkeeporiginal} The \name{taylorkeeporiginal} switch determines whether the \nameref{taylor} operator keeps the expression to be expanded for later use. Default is \name{on}. \end{Switch} \begin{Operator}{taylororiginal} \name{taylororiginal} extracts the original expression from a Taylor kernel. \begin{Syntax} \name{taylororiginal}\(\arg{taylor\_kernel}\) \end{Syntax} If the argument is not a Taylor kernel, or if the expression was not kept, an error is signaled. \end{Operator} \begin{Variable}{taylorprintterms} Only a certain number of (non-zero) coefficients of a Taylor kernel are printed usually. If there are more, \verb|...| is printed as part of the expression to indicate this. The number of terms printed is given by the value of the shared algebraic variable \nameref{taylorprintterms}. Allowed values are integers and the special identifier \name{all}. The latter setting specifies that all terms are to be printed. The default setting is $5$. \end{Variable}