Q: Contour integral
- To: mathgroup@smc.vnet.net
- Subject: [mg10792] Q: Contour integral
- From: Patrick Van Esch <pvanesch@vub.ac.be>
- Date: Thu, 5 Feb 1998 00:58:36 -0500
- Organization: Vrije Universiteit Brussel
Hi folks,
I have the following question: I've been reading "Mathematica for
scientists and engineers", and there is an example on how to calculate
numerically a contour integral:
NContourIntegrate[f_,par:(z_->g_),{t_,a_,b_}]:=
NIntegrate[Evaluate[(f/.par)D[g,t]],{t,a,b}]
When applying this to a limacon:
NContourIntegrate[1/(z-1/2),z->Exp[I t](2Cos[t]+1),{t,0,2 Pi}]
one gets the right answer:
\!\(3.33066907387546962`*^-16 + 12.5663706143520892`\ I\)
(4pi I)
However, when modifying the numerical integration into an analytic one,
ContourIntegrate[f_,par:(z_->g_),{t_,a_,b_}]:=
Integrate[Evaluate[(f/.par)D[g,t]],{t,a,b}]
The answer that is obtained is wrong:
2 Pi I
Any ideas ?
cheers,
Patrick.
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