Re: Residue Function

*To*: mathgroup at smc.vnet.net*Subject*: [mg76370] Re: Residue Function*From*: CKWong <CKWong.P at gmail.com>*Date*: Sun, 20 May 2007 02:39:21 -0400 (EDT)*References*: <f2mcqa$kdg$1@smc.vnet.net>

I'm not sure what's going on here. As I understand it, residues are used to evaluate contour integrals because the former is always easier to calculate than the latter. Here, every one is going the opposite direction. The incompetence of the function Residue is to be deplored but it is easily remedied. If one remembers that the function Series is meant to provide the Taylor series, it can be easily adapted to get the Laurent Series. Take the present example of finding the residue of Exp[2/z] at z=0, the proper way to proceed is as follows Series[ Exp[2x], {x,0,1}] /. x->1/z There is no need to bring in the pole at infinity, which simply makes thing worse as you don't seem to know how the residue at infinity is defined (see my other reply to your earlier posting). I apologize in advance if I sound over-bearing. But it's rather frustrating to witness the mangling of an elegant subject like contour integrals.