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Re: Real and Imaginary Parts of complex functions

• To: mathgroup at smc.vnet.net
• Subject: [mg129938] Re: Real and Imaginary Parts of complex functions
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Wed, 27 Feb 2013 03:05:57 -0500 (EST)
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• References: <20130226060933.C3A19687D@smc.vnet.net>

Just use ComplexExpand with assumes that all variables are Reals
unless otherwise specified.

Re[x + y*I] // ComplexExpand

x

Re[1/(x + y*I)] // ComplexExpand

x/(x^2 + y^2)


Bob Hanlon


On Tue, Feb 26, 2013 at 1:09 AM, Brentt <brenttnewman at gmail.com> wrote:
>
> 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?
>
>

• References:
  • Real and Imaginary Parts of complex functions
    • From: Brentt <brenttnewman@gmail.com>