Re: Defining Real expressions

*To*: mathgroup at smc.vnet.net*Subject*: [mg8509] Re: Defining Real expressions*From*: hans.steffani at e-technik.tu-chemnitz.de (Hans Steffani)*Date*: Thu, 4 Sep 1997 02:19:55 -0400*Organization*: University of Technology Chemnitz, FRG*Sender*: owner-wri-mathgroup at wolfram.com

Marco Beleggia <beleggia at gpxbof.df.unibo.it> writes: >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. I do not understand the problem: Integrate[y/(x^2+y^2) Exp[-I p y],{y,-Infinity,Infinity}] delivers 2 2 1/4 Sqrt[p ] Pi -I (p ) Sqrt[Pi] Sqrt[-----------] 2 p ------------------------------------- 2 2 Sqrt[p ] Sqrt[x ] E Maybe ComplexExpand[] helps in your case. h.f.s. [cc,fup] -- Hans Friedrich Steffani Institut fuer Elektrische Maschinen und Antriebe, TU Chemnitz-Zwickau mailto:hans.steffani at e-technik.tu-chemnitz.de http://www.tu-chemnitz.de/~hfst/