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Re: Defining Real Expressions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg8535] Re: Defining Real Expressions
  • From: Raya Firsov-Khanin <raya at mech.ed.ac.uk>
  • Date: Sat, 6 Sep 1997 23:16:07 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

Marco Beleggia wrote:

<I must evaluate an Integral in which I'd like to assign real values to
<some parameters, but I don't know how to do that.

<For example, in the following integral (a Fourier Transform): 

<f[x_,p_]=Integrate[y/(x^2+y^2) Exp[-I p y],{y,-Infinity,Infinity}],

<p should be a real parameter. The output given by Mathematica is
<conditioned to Im[p]==0, such as If[Im[p]==0,....,....], which is not
<easy to handle, and I'd like to avoid this complication.

<Is it possible ?

The simplest way to deal with this is to declare

p/:Im[p]=0

Then, f[x, p] will give you an answer (if Arg[x^2]!=\[Pi]).

-------		
		              Raya Khanin


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