       RE: Trick for getting the comples conjugate in symbolic calculations?

• To: mathgroup at smc.vnet.net
• Subject: [mg30330] RE: [mg30297] Trick for getting the comples conjugate in symbolic calculations?
• From: "David Park" <djmp at earthlink.net>
• Date: Sat, 11 Aug 2001 03:39:51 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Norbert,

I don't know if I understand the example you have presented. In any case,
here is a similar example.

z1 = x1 + I y1;
z2 = x2 + I y2;

z1 Conjugate[z2] // ComplexExpand
x1*x2 + y1*y2 + I*(x2*y1 - x1*y2)

In common use you may wish to use ComplexExpand in the form
ComplexExpand[expression, TargetFunctions -> {Re, Im}]
otherwise Mathematica uses whatever it finds convenient for target
functions.

It really does take some practice to learn how to use Mathematica with
complex calculations. For some simple jobs you may have to write your own
routines.

David Park

> From: riefler at iwt.uni-bremen.de [mailto:riefler at iwt.uni-bremen.de]
To: mathgroup at smc.vnet.net
>
> Hi
>
> I read in the older news that the numeric functions real / Re and imag
> / Im for  / Mathematica won't do its job because of some
> ambiguity. The same holds for the complex conjugate conj / Conjugate.
>
> Is there a trick to get anyway the algebraic solution of for example
> (x1+i*y1)*conj(x2+i*y2) / (x1+i*y1)*Conjugate(x2+i*y2) in Mathematica?
>
>
> Thanks a lot
>
> Norbert
>

```

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