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Re: Question for using complex variables


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)

Cheers,
	Paul 

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