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MathGroup Archive 2004

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Re: How to solve nonlinear equations?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52526] Re: How to solve nonlinear equations?
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 1 Dec 2004 05:57:41 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <cohj9d$1nr$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

a) learn the correct syntax of Mathematica
b) read the Mathematica book carefully
c) type:

eqns = {20.428836553499018 - Log[X1] ==
468/67*X1 + 5790/1273*X2 - 66257/1273*X3 - 24660/1273*X4 -
79150/1273*X5,
17.011108423692498 - Log[X2] ==
5790/1273*X1 + 6294/1273*X2 - 66257/1273*X3 - 24660/1273*X4 -
403.8069285*X5, -29.72639373695347 - Log[X3] == -66257/1273*X1 -
66257/1273*X2 - 2*X3, -26.273726271581616 -
Log[X4] == -24660/1273*X1 - 24660/1273*X2 +
10.15330715*X4, -38.76695085346396 - Log[X5] == -79150/1273*X1 -
403.8069285*X2 - 10.67374705*X5}

FindRoot[eqns, {{X1, 1}, {X2, 1}, {X3, 1}, {X4, 1}, {X5, 1}}]



Regards

  Jens


"Wei Wang" <weiwang at baosteel.com> schrieb im Newsbeitrag 
news:cohj9d$1nr$1 at smc.vnet.net...
> How to solve the following equations, where X1, X2, X3, X4 and X5 are 
> variables?
>
> eqns = {20.428836553499018-ln(X1) == 
> 468/67*X1+5790/1273*X2-66257/1273*X3-24660/1273*X4-79150/1273*X5, 
> 17.011108423692498-ln(X2) == 
> 5790/1273*X1+6294/1273*X2-66257/1273*X3-24660/1273*X4-403.8069285*X5, -29.72639373695347-ln(X3) 
> == -66257/1273*X1-66257/1273*X2-2*X3, -26.273726271581616-ln(X4) 
> == -24660/1273*X1-24660/1273*X2+10.15330715*X4, -38.76695085346396-ln(X5) 
> == -79150/1273*X1-403.8069285*X2-10.67374705*X5};
> 



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