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Re: declaring variables
Posted:
Sep 13, 1996 1:00 PM


dh61@rs3.hrz.thdarmstadt.de (Burkhardt Goedde) wrote:
>Dear math users, >just a simple problem, but I got no answer from thew book. >Re[x + I y] gives >Re[x + I y] >whereas >Re[2 + 3 I] >gives 2 >How could I tell Mathematica that x and y are real numbers?
There is a package <<Algebra`ReIm` that lets you specify that given variables are purely real. Try the following:
In[5]:= Needs["Algebra`ReIm`"]
Im[x]^=0;
Im[y]^=0;
Re[x + I y]
Im[x + I y]
Out[8]= x Out[9]= y
The up definitions make the assignment associated with x and y rather than with Im...
Hope this helps Vicki
________________________________________________________________________
Victoria Steblina Email: vvs124@rsphy1.anu.edu.au Optical Sciences Centre Tel: 61 6 249 5129 Australian National University Fax: 61 6 249 5184



