@@ -1,189 +1,189 @@ -\documentstyle[11pt,reduce]{article} -\title{{\bf RESIDUE Package for {\tt REDUCE}}} -\author{Wolfram Koepf\\ email: {\tt Koepf@zib-berlin.de}} -\date{April 1995 : ZIB Berlin} -\begin{document} -\maketitle -\def\Res{\mathop{\rm Res}\limits} -\newcommand{\C}{{\rm {\mbox{C{\llap{{\vrule height1.52ex}\kern.4em}}}}}} - -This package supports the calculation of residues. The residue -$\Res_{z=a} f(z)$ of a function $f(z)$ at the point $a\in\C$ is defined -as -\[ -\Res_{z=a} f(z)= -\frac{1}{2 \pi i}\oint f(z)\,dz -\;, -\] -with integration along a closed curve around $z=a$ with winding number 1. - -If $f(z)$ is given by a Laurent series development at $z=a$ -\[ -f(z)=\sum_{k=-\infty}^\infty a_k\,(z-a)^k -\;, -\] -then -\begin{equation} -\Res\limits_{z=a} f(z)=a_{-1} -\;. -\label{eq:Laurent} -\end{equation} -If $a=\infty$, one defines on the other hand -\begin{equation} -\Res\limits_{z=\infty} f(z)=-a_{-1} -\label{eq:Laurent2} -\end{equation} -for given Laurent representation -\[ -f(z)=\sum_{k=-\infty}^\infty a_k\,\frac{1}{z^k} -\;. -\] - -The package is loaded by the statement - -\begin{verbatim} -1: load residue; -\end{verbatim} - -It contains two REDUCE operators: - -\begin{itemize} -\item -{\tt residue(f,z,a)} determines the residue of $f$ at the point $z=a$ -if $f$ is meromorphic at $z=a$. The calculation of residues at essential -singularities of $f$ is not supported. -\item -{\tt poleorder(f,z,a)} determines the pole order of $f$ at the point $z=a$ -if $f$ is meromorphic at $z=a$. -\end{itemize} -Note that both functions use the {\tt taylor} package in -connection with representations (\ref{eq:Laurent})--(\ref{eq:Laurent2}). - -Here are some examples: - -\begin{verbatim} -2: residue(x/(x^2-2),x,sqrt(2)); - - 1 ---- - 2 - -3: poleorder(x/(x^2-2),x,sqrt(2)); - -1 - -4: residue(sin(x)/(x^2-2),x,sqrt(2)); - - sqrt(2)*sin(sqrt(2)) ----------------------- - 4 - -5: poleorder(sin(x)/(x^2-2),x,sqrt(2)); - -1 - -6: residue(1/(x-1)^m/(x-2)^2,x,2); - - - m - -7: poleorder(1/(x-1)/(x-2)^2,x,2); - -2 - -8: residue(sin(x)/x^2,x,0); - -1 - -9: poleorder(sin(x)/x^2,x,0); - -1 - -10: residue((1+x^2)/(1-x^2),x,1); - --1 - -11: poleorder((1+x^2)/(1-x^2),x,1); - -1 - -12: residue((1+x^2)/(1-x^2),x,-1); - -1 - -13: poleorder((1+x^2)/(1-x^2),x,-1); - -1 - -14: residue(tan(x),x,pi/2); - --1 - -15: poleorder(tan(x),x,pi/2); - -1 - -16: residue((x^n-y^n)/(x-y),x,y); - -0 - -17: poleorder((x^n-y^n)/(x-y),x,y); - -0 - -18: residue((x^n-y^n)/(x-y)^2,x,y); - - n - y *n ------- - y - -19: poleorder((x^n-y^n)/(x-y)^2,x,y); - -1 - -20: residue(tan(x)/sec(x-pi/2)+1/cos(x),x,pi/2); - --2 - -21: poleorder(tan(x)/sec(x-pi/2)+1/cos(x),x,pi/2); - -1 - -22: for k:=1:2 sum residue((a+b*x+c*x^2)/(d+e*x+f*x^2),x, - part(part(solve(d+e*x+f*x^2,x),k),2)); - - b*f - c*e ------------ - 2 - f - -23: residue(x^3/sin(1/x)^2,x,infinity); - - - 1 ------- - 15 - -24: residue(x^3*sin(1/x)^2,x,infinity); - --1 -\end{verbatim} -\iffalse -7: for k:=1:3 sum -7: residue((a+b*x+c*x^2+d*x^3)/(e+f*x+g*x^2+h*x^3),x, -7: part(part(solve(e+f*x+g*x^2+h*x^3,x),k),2)); - - -***** CATASTROPHIC ERROR ***** -("gcdf failed" (root_of (plus e (times f x_) (times g (expt x_ 2)) (times h ( -expt x_ 3))) x_ tag_2) (times (root_of (plus e (times f x_) (times g (expt -x_ 2)) (times h (expt x_ 3))) x_ tag_2) h)) - - - -***** Please send output and input listing to A. C. Hearn -\fi -Note that the residues of factorial and $\Gamma$ function terms are -not yet supported. - -\end{document} - +\documentstyle[11pt,reduce]{article} +\title{{\bf RESIDUE Package for {\tt REDUCE}}} +\author{Wolfram Koepf\\ email: {\tt Koepf@zib-berlin.de}} +\date{April 1995 : ZIB Berlin} +\begin{document} +\maketitle +\def\Res{\mathop{\rm Res}\limits} +\newcommand{\C}{{\rm {\mbox{C{\llap{{\vrule height1.52ex}\kern.4em}}}}}} + +This package supports the calculation of residues. The residue +$\Res_{z=a} f(z)$ of a function $f(z)$ at the point $a\in\C$ is defined +as +\[ +\Res_{z=a} f(z)= +\frac{1}{2 \pi i}\oint f(z)\,dz +\;, +\] +with integration along a closed curve around $z=a$ with winding number 1. + +If $f(z)$ is given by a Laurent series development at $z=a$ +\[ +f(z)=\sum_{k=-\infty}^\infty a_k\,(z-a)^k +\;, +\] +then +\begin{equation} +\Res\limits_{z=a} f(z)=a_{-1} +\;. +\label{eq:Laurent} +\end{equation} +If $a=\infty$, one defines on the other hand +\begin{equation} +\Res\limits_{z=\infty} f(z)=-a_{-1} +\label{eq:Laurent2} +\end{equation} +for given Laurent representation +\[ +f(z)=\sum_{k=-\infty}^\infty a_k\,\frac{1}{z^k} +\;. +\] + +The package is loaded by the statement + +\begin{verbatim} +1: load residue; +\end{verbatim} + +It contains two REDUCE operators: + +\begin{itemize} +\item +{\tt residue(f,z,a)} determines the residue of $f$ at the point $z=a$ +if $f$ is meromorphic at $z=a$. The calculation of residues at essential +singularities of $f$ is not supported. +\item +{\tt poleorder(f,z,a)} determines the pole order of $f$ at the point $z=a$ +if $f$ is meromorphic at $z=a$. +\end{itemize} +Note that both functions use the {\tt taylor} package in +connection with representations (\ref{eq:Laurent})--(\ref{eq:Laurent2}). + +Here are some examples: + +\begin{verbatim} +2: residue(x/(x^2-2),x,sqrt(2)); + + 1 +--- + 2 + +3: poleorder(x/(x^2-2),x,sqrt(2)); + +1 + +4: residue(sin(x)/(x^2-2),x,sqrt(2)); + + sqrt(2)*sin(sqrt(2)) +---------------------- + 4 + +5: poleorder(sin(x)/(x^2-2),x,sqrt(2)); + +1 + +6: residue(1/(x-1)^m/(x-2)^2,x,2); + + - m + +7: poleorder(1/(x-1)/(x-2)^2,x,2); + +2 + +8: residue(sin(x)/x^2,x,0); + +1 + +9: poleorder(sin(x)/x^2,x,0); + +1 + +10: residue((1+x^2)/(1-x^2),x,1); + +-1 + +11: poleorder((1+x^2)/(1-x^2),x,1); + +1 + +12: residue((1+x^2)/(1-x^2),x,-1); + +1 + +13: poleorder((1+x^2)/(1-x^2),x,-1); + +1 + +14: residue(tan(x),x,pi/2); + +-1 + +15: poleorder(tan(x),x,pi/2); + +1 + +16: residue((x^n-y^n)/(x-y),x,y); + +0 + +17: poleorder((x^n-y^n)/(x-y),x,y); + +0 + +18: residue((x^n-y^n)/(x-y)^2,x,y); + + n + y *n +------ + y + +19: poleorder((x^n-y^n)/(x-y)^2,x,y); + +1 + +20: residue(tan(x)/sec(x-pi/2)+1/cos(x),x,pi/2); + +-2 + +21: poleorder(tan(x)/sec(x-pi/2)+1/cos(x),x,pi/2); + +1 + +22: for k:=1:2 sum residue((a+b*x+c*x^2)/(d+e*x+f*x^2),x, + part(part(solve(d+e*x+f*x^2,x),k),2)); + + b*f - c*e +----------- + 2 + f + +23: residue(x^3/sin(1/x)^2,x,infinity); + + - 1 +------ + 15 + +24: residue(x^3*sin(1/x)^2,x,infinity); + +-1 +\end{verbatim} +\iffalse +7: for k:=1:3 sum +7: residue((a+b*x+c*x^2+d*x^3)/(e+f*x+g*x^2+h*x^3),x, +7: part(part(solve(e+f*x+g*x^2+h*x^3,x),k),2)); + + +***** CATASTROPHIC ERROR ***** +("gcdf failed" (root_of (plus e (times f x_) (times g (expt x_ 2)) (times h ( +expt x_ 3))) x_ tag_2) (times (root_of (plus e (times f x_) (times g (expt +x_ 2)) (times h (expt x_ 3))) x_ tag_2) h)) + + + +***** Please send output and input listing to A. C. Hearn +\fi +Note that the residues of factorial and $\Gamma$ function terms are +not yet supported. + +\end{document} +