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MathGroup Archive 2005

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ComplexExpand confusion

  • To: mathgroup at smc.vnet.net
  • Subject: [mg60109] ComplexExpand confusion
  • From: mike_in_england2000 at yahoo.co.uk
  • Date: Sat, 3 Sep 2005 02:05:58 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi

The Mathematica help system says that

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

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

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

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.

Thanks
Mike


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