Re: Re-defining Log over it's branch cut

*To*: mathgroup at smc.vnet.net*Subject*: [mg77507] Re: Re-defining Log over it's branch cut*From*: chuck009 <dmilioto at comcast.com>*Date*: Mon, 11 Jun 2007 04:21:14 -0400 (EDT)

Hello Dimitris, Is there a way to have Mathematica do this substitution internally when evaluating powers such as z^s? The reason I ask is that I'm working on the contour integral expressions for Zeta and Polylog which use the Hankel contour. This contour requires the substitutions z=rExp[pi i] and z=r Exp[-pi i]. However, Mathematica assigns the "standard convention" of pi to the argument for both cases. For example if I specify: In[248]:= N[z^(s-1)/.z->r Exp[-Pi I]] Mathematica return an answer that is actually: Exp[(s-1)(Log[r]+pi i] and not: Exp[(s-1)(Log[r]-pi i] I realize that's the standard convention. Just would make my code a little less messy if I didn't have to do the expansion myself and "manually" insert the -pi i factor.

**Follow-Ups**:**Re: Re: Re-defining Log over it's branch cut***From:*Carl Woll <carlw@wolfram.com>