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MathGroup Archive 2001

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Re: complex coefficients and rules...

  • To: mathgroup at
  • Subject: [mg28261] Re: [mg28203] complex coefficients and rules...
  • From: "Mark Harder" <harderm at>
  • Date: Fri, 6 Apr 2001 01:53:09 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

    In[194]:= FullForm[Exp[-4 I y] /. I -> -I ]
Out[194]//FullForm=  Power[E, Times[Complex[0, -4], y]]

In[191]:=conj = Exp[-4 I y] /. Complex[a_, b_] -> Complex[a, -b]
                        4 I y
Out[191]=   E

In[193]:= FullForm[conj]
Out[193]//FullForm= Power[E, Times[Complex[0, 4], y]]

-mark harder

-----Original Message-----
From: Richard Easther <easther at>
To: mathgroup at
Subject: [mg28261] [mg28203] complex coefficients and rules...

>I am having some trouble applying some simple rules to complex
>For instance,
> Exp[-4 I y] /. I-> -I
> Exp[-4 I y]
>This seemed a bit odd, so I looked at the "full form" and found,
>Power[E, Times[Complex[0, -4], y]]
>However, trying the match 
> Exp[-4 I y] /. a_ I -> -a I
>doesn't work either, since FullForm[a I ]  is Times[Complex[0, -1], a]
>and so the patterns do not match.  
>All I want is a simple complex conjugate (the Conjugate function does
>not assume that y is real), that maps I->-I. The more tricky 
> Exp[-4 I y] /. Complex[a_ ,b_] -> Complex[a,-b] 
>does work, but it is seems a little cumbersome.
>In any case my question is: is there a general way to avoid having to do
>this, or is Mathematica always going to assume that any algebraic
>constant is potentially complex?

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