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MathGroup Archive 2005

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Re: ComplexExpand confusion

  • To: mathgroup at
  • Subject: [mg60141] Re: [mg60109] ComplexExpand confusion
  • From: "David Park" <djmp at>
  • Date: Sun, 4 Sep 2005 03:02:04 -0400 (EDT)
  • Sender: owner-wri-mathgroup at


The answer is very simple! Just look at...

ComplexExpand[(-1)^(1/4)] // Trace

Could anything be clearer?

David Park
djmp at 

From: mike_in_england2000 at
To: mathgroup at
[mailto:mike_in_england2000 at]


The Mathematica help system says that

"ComplexExpand[expr] expands expr assuming that all variables are

which is fine and explains why expressions such as
ComplexExpand[Conjugate[x +I y]] work.All seems obvious so far.

What is confusing me though is why does


give the result

(1 + I)/Sqrt[2]

I know this the correct result but in the expression (-1)^(1/4) there
are no variables.  The numbers involved are real so what on earth is
ComplexExpand doing? Is this a stupid question? Should I have drank
more coffee before posting this.


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