NIntegrate with change of variables

*To*: mathgroup at smc.vnet.net*Subject*: [mg77441] NIntegrate with change of variables*From*: chuck009 <dmilioto at comcast.com>*Date*: Sat, 9 Jun 2007 05:25:06 -0400 (EDT)

Hi, I'm working on contour integrals using NIntegrate. Can I specify a transformation rule that would replace both the variable of integration as well as the differential? For example, suppose I wish to integrate f(z)dz around the unit circle, that is z=Exp[i t]. Well I could make the transformation: NIntegrate[f[z] /. z->Exp[i t],{t,-pi, pi}] but that does not replace dz with its equivalent in terms of t, that is: dz=i Exp[i t] dt The correct form to integrate would be: NIntegrate[f[Exp[i t]] i Exp[i t],{t,-pi, pi}] Is there a way to define a transformation rule that would make both those substitutions for unspecified z=g(t)?