ASKSAGE: Sage Q&A Forum - Latest question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sat, 07 Jul 2012 01:34:55 -0500calculating residue with maxima_methodshttp://ask.sagemath.org/question/9141/calculating-residue-with-maxima_methods/The following used to work around six months ago on sagenb.org:
var('x')
var('t')
( x/((4*x - 1)*(t^2 - t + x)) ).maxima_methods().residue(t,(1-sqrt(1-4*x))/2)
but now it returns zero which is incorrect. Can anybody help me get the correct answer again?Stefán IngiSat, 07 Jul 2012 01:34:55 -0500http://ask.sagemath.org/question/9141/Can sage find the poles of a complex function, and the residues at those poles?http://ask.sagemath.org/question/8072/can-sage-find-the-poles-of-a-complex-function-and-the-residues-at-those-poles/Hi all,
I searched the SAGE reference and didn't find the word residue in realtion to functions of a complex variable. The function I'm working with is not the ratio of two polynomials in Z, which can be factored out to find the poles and zeros. It's actually like this:
f(z) = A* sinh(z)/ (B* z^2* sinh(z)+ C* z* cosh(z)-D* sin(z))
got this from laplace transforming a partial differential equation I want to solve. I'm following the technique used in a paper I'm trying to apply to a different geometry/coordinate system, and if I can get the residues at the poles, I can get a series solution to the PDE. However, I can't fill in the omitted steps in the paper due to my never having taken a course in complex variables. Hence my interest in finding the residues at the poles programmatically.
I would greatly appreciate a clue or two. Thank you.
Mark GMon, 11 Apr 2011 12:49:16 -0500http://ask.sagemath.org/question/8072/