Date: Feb 27, 2013 3:04 AM
Author: Bill Rowe
Subject: Re: Real and Imaginary Parts of complex functions

On 2/26/13 at 1:09 AM, brenttnewman@gmail.com (Brentt) wrote:

>I was wondering why this works

>IN[]:= Refine[Re[x + y I], Element[x , Reals] && Element[y , Reals]]

>Out[]:= x

>But this does not

>In[]:= Refine[Re[1/(x + y I)], Element[x , Reals] && Element[y ,
>Reals]]


>Out[]:= Re[1/(x + y I)]

>Is there a nice built in way to get the real and imaginary parts of
>a complex function?


ComplexExpand, for example:

In[3]:= List @@ ComplexExpand[1/(x + y I)]

Out[3]= {x/(x^2 + y^2), -((I*y)/(x^2 + y^2))}