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MathGroup Archive 2007

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Re: How to choose real positive solutions?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg74306] Re: How to choose real positive solutions?
  • From: Peter Breitfeld <phbrf at t-online.de>
  • Date: Sun, 18 Mar 2007 00:44:12 -0500 (EST)
  • References: <etg46h$ijg$1@smc.vnet.net>

mandix schrieb:
> Hi,
> suppose I want to solve a system of 3 equations and 3 unknowns
> (polynomial of degree whatever, say n). Is there a way to tell NSolve
> to return only real and positive solutions (and ignore the rest)?
>
> thanks you so much,
>
> Manfred
>
Manfred,

first define a pattern which matches complex Numbers e.g:

MuComplex= _?(!FreeQ[Chop[N[#],10^-13],_Complex]&)

then do:
DeleteCases[NSolve["whatever"],MuComplex]

Gruss Peter
-- 
==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de


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