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Re: Problem NSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg90653] Re: Problem NSolve
  • From: Alois Steindl <Alois.Steindl at tuwien.ac.at>
  • Date: Fri, 18 Jul 2008 04:00:23 -0400 (EDT)
  • References: <g5n45f$sb8$1@smc.vnet.net>

Jorge <jorgecerrillo at gmail.com> writes:


> As soon as I have programmed the problem to resolving, 23 equations with 23 variables, I use the function Nsolve, but the program returns to me the following message of mistake 
>
> General::ivar: 0 is not a valid variable. >>
>
> I have programmed my problem of the following form:
>
> ecu{lhs1==0,lhs2=0,...,lhs23}
> sol=Nsolve[ecu{var1,var2,...,var23}]
>
>
Hello,
when working with any CAS you need to precisely follow the semantics!
For example
ecu{lhs1==0,lhs2=0,...,lhs23}
is not a proper statement in Mathematica.
Moreover the first entry lhs1==1 is a test, lhs2=0 is an assignment
(assigns 0 to the variable lhs2; that might be the culprit for the
error message) and lhs23 is just an expession. YOu didn't show amy
detail, how you specified those lhsxx terms, so how could we help you
at all?
Also the call to Nsolve is stated incorrectly.
Are you sure, that you need to use Nsolve, maybe NDSolve is what you
are looking for.
Alois


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