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MathGroup Archive 2004

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Re: A way around the limitations of Re[] and Im[]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg51125] Re: A way around the limitations of Re[] and Im[]
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Tue, 5 Oct 2004 04:37:15 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <cjr8lg$opp$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

a Real is the head of floating point numbers and it is not
a good idea to attatch a function definition to it.
And look what
ComplexExpand[Re[a + I*b]]

does.

Regards

  Jens



"Carlos Felippa" <carlos at colorado.edu> schrieb im Newsbeitrag
news:cjr8lg$opp$1 at smc.vnet.net...
> As you know, Re[expr] and Im[expr] are left unevaluated when expr is
> not numeric.  I had good luck in simple cases with the following
> substitution trick:
>
>         Real[c_]:=c/.I->0;     Imag[c_]:=(c-Real[c])/.I->1;
>
> Do you see any problem with these definitions?
>



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