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Re: Problem NSolve

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  • Subject: [mg90673] Re: Problem NSolve
  • From: Bill Rowe <readnews at>
  • Date: Fri, 18 Jul 2008 04:04:08 -0400 (EDT)

On 7/17/08 at 5:36 AM, jorgecerrillo at (Jorge) wrote:

>Hello! To begin to ask for excuses you for my English poor level...
>I am a Spanish student of Chemical Engineering. Now I am employed at
>the simulation of a series of chemical reactions with Mathematica.

>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}]

>Might someone help?

There really is no way for someone to determine what the
specific problem is without the code leading to this error. Most
likely, there is a typo in what you entered. Possibly using "="
where you meant to use "==". In fact, the second argument to the
function ecu in the snippet you posted sets lhs2 to 0. Perhaps
this should have been lhs2==0 instead.

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