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MathGroup Archive 2005

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Re: refining expression in terms of real numbers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg58747] Re: refining expression in terms of real numbers
  • From: Peter Pein <petsie at dordos.net>
  • Date: Sun, 17 Jul 2005 03:04:00 -0400 (EDT)
  • References: <dba4l5$elr$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Mukhtar Bekkali schrieb:
> My expression is real for all values of gamma between half and one (I
> plotted it just to be sure), yet the general solution that Mathametica
> generates may imply that I have an unreal solution, an impression that
> I would like to avoid. Is there a way to make Mathematica refine
> solutions in terms of real numbers. Here is the input:
>
> \!\(expr := Refine[Root[\(-160\) + 783\ =CE=B3 + 54\
>             =CE=B3\^2 - 1059\ #1 - 540\ =CE=B3\ #1 + 504\ #1\^2 + 80\ #=
1\^3 &,
> 2] //
>                  ToRadicals, 1\/2 < =CE=B3 < 1] //
> Simplify\[IndentingNewLine]
>   expr\[IndentingNewLine]
>   \(Plot[expr, {=CE=B3, 1\/2, 1}];\)\)
>
> Thanks, Mukhtar Bekkali
>
Hi,

you can find a notebook with a solution at
http://people.freenet.de/Peter_Berlin/Mathe/Mukhtar.nb

does anyone know, why Mathematica changes the index of the Root[,index],
while evaluating FullSimplify[ComplexExpand[Re[Root[...,2]]]] ?

Regards,
P^2
--
Peter Pein
Berlin
http://people.freenet.de/Peter_Berlin/


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