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Re: Question for using complex variables

• To: mathgroup at smc.vnet.net
• Subject: [mg13743] Re: Question for using complex variables
• From: Daniel Lichtblau <danl>
• Date: Wed, 19 Aug 1998 01:38:31 -0400
• Organization: Wolfram Research, Inc.
• References: <6r10kv$fjg@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Chongdae Park wrote:
> 
> Hellow !!!
> 
> I'd like to use complex variable computation, but I do not know how.
> Here is my program;
> Here, x, y, w, and z are all real values. Then I expected
> 
> Complex[x,y]*Complex[w,z]=(xw-yz)+I(xz+yw)
> 
> But I can't get it. Please let me know how .
> -----------------------------------------------------------------------
>                                    Chongdae Park
>                                    Dept. of Electronic Engineering
>                                    Myongji University
>                                    San 38-2, Nam-Dong, Yongin
>                                    Kyoungki-Do, Korea
>                                    Zipcode : 449-728
>                                    Phone   : +82-335-30-6379
>                                    Fax     : +82-335-21-0271
>                                    email   : cdpark at wh.myongji.ac.kr
> =======================================================================


The best way I know to do this sort of thing in Mathematica is to use
ComplexExpand. For example:

In[68]:= ComplexExpand[(x+I*y)*(w+I*z)] Out[68]= w x - y z + I (w y + x
z)


Daniel Lichtblau
Wolfram Research