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MathGroup Archive 1998

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Re: Question for using complex variables

  • To: mathgroup at
  • Subject: [mg13772] Re: Question for using complex variables
  • From: Paul Abbott <paul at>
  • Date: Mon, 24 Aug 1998 05:07:22 -0400
  • Organization: University of Western Australia
  • References: <6r10kv$>
  • Sender: owner-wri-mathgroup at

Chongdae Park wrote:

> Here, x, y, w, and z are all real values. Then I expected
> Complex[x,y]*Complex[w,z]=(xw-yz)+I(xz+yw)

First, note that 

  In[1]:= ?Complex
  "Complex is the head used for complex numbers."

so, to work with complex variables in explicit form, you should not use
Complex but instead enter them directly as x+I y, etc.

Second, ComplexExpand is the operator you want for simplifying complex
expressions (assuming that the variables x,y,w,z are real):

  In[2]:= ComplexExpand[(x + I y) (w + I z)]
  Out[2]= w x - y z + I (w y + x z)


Paul Abbott                                   Phone: +61-8-9380-2734
Department of Physics                           Fax: +61-8-9380-1014
The University of Western Australia            Nedlands WA  6907       
mailto:paul at  AUSTRALIA              

            God IS a weakly left-handed dice player

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