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Re: Real and Imaginary Parts of complex functions


On 2013-02-26 06:09:00 +0000, Brentt said:

> Hello,
> 
> 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?

You can use ComplexExpand for this.

In[8]:= ComplexExpand[Re[1/(x + y I)]]
Out[8]= x/(x^2 + y^2)

See also http://mathematica.stackexchange.com/q/9340/12 and the links within.




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