Colleagues,

Let me add that solving nonlinear systems of equations (and many other NLPs) is often a global optimization problem. Hence, the user needs a “sufficiently good” initial solution guess, or should perhaps [also] use global optimization software.

Best wishes,

Janos

Janos D. Pinter, PhD, DSc

Visiting Professor

Department of Industrial Engineering

Ozyegin University

Kusbakisi Cad. No. 2

34662 Altunizade, Uskudar - Istanbul

TURKEY

Tel. +90 216 559 2332

Fax:+90 216 559 2470

janos.pinter@ozyegin.edu.tr

http://www.ozyegin.edu.tr

President

Pinter Consulting Services, Inc., Canada

janos.d.pinter@gmail.com

http://www.pinterconsulting.com

On Wed, Apr 27, 2011 at 9:32 AM, zahra adel wrote:

Hi,

As you know, nonlinear programming is highly dependent on the way it is formulated and on its initial values. I recommmend you read CONOPT manual (CONOPT is normally the default nonlinear solver), especially pages 10-16. You can download the file at www.gams.com/dd/docs/solvers/conopt.pdf

I hope it helps you.

Zahra.

From: saman

To: gamsworld

Sent: Mon, April 25, 2011 9:37:35 PM

Subject: system of nonlinear equation

Hello everybody

I’m beginner in GAMS then I have a question about solving nonlinear

equation system (n equations - n unknowns)

for example I write this code for a simple nonlinear equation solving:

variable fi

equation e1;

e1… 2*5.51/(5.51-fi)+3*2.32/(2.32-fi)+1*5/(1-fi)=e=0;

model root /e1/ ;

fi.l=3;

solve root using nlp minimizing fi;

it’s work truly but this code find one root near fi.l=3 and also this

is just one equation!

when I have a system of nonlinear equation with index i for any

variable in equation j, how can I solve it?

yours sincerely!

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