Solving without Min or Max

Problems with modeling
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paganini
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Solving without Min or Max

Post by paganini »

Hi there
I'm trying to solve some equations without any optimizations and any minimizing or maximizing.
and I know there is a solver called "CNS" which is capable to solve without any Min or Max statement but it has to be a square system.
so the question is how to solve a non-square problem without minimizing or maximizing???
thank you all.
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Renger
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Re: Solving without Min or Max

Post by Renger »

Hi
You could make it an optimization problem by adding following:

Code: Select all


variable OBJ objective
equation dummy  Dummy objective;

dummy..
    OBJ =E= 1;
Then solve the model maximizing OBJ. GAMS will find OBJ being equal to 1 solves the problem while at the same time solving the other equations.

I hope this helps.
Cheers
Renger
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Enjoy modeling even more: Read my blog on modeling at The lazy economist
paganini
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Re: Solving without Min or Max

Post by paganini »

thank you Renger for your reply.
femibode
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Re: Solving without Min or Max

Post by femibode »

Renger wrote: 3 years ago Hi
You could make it an optimization problem by adding following:

Code: Select all


variable OBJ objective
equation dummy  Dummy objective;

dummy..
    OBJ =E= 1;
Then solve the model maximizing OBJ. GAMS will find OBJ being equal to 1 solves the problem while at the same time solving the other equations.

I hope this helps.
Cheers
Renger
Thanks for this tread. I having similar situation where I wanted to have model run without obj equation. I implemented this procedure of dummy obj but having solution:

**** SOLVER STATUS 4 Terminated By Solver
**** MODEL STATUS 14 No Solution Returned
**** OBJECTIVE VALUE 1.0000

RESOURCE USAGE, LIMIT 3.844 9000000000.000
ITERATION COUNT, LIMIT 0 2000
EVALUATION ERRORS 0 0

MsNlp Terminated When Iteration Count Exceeded Limit of 1000

and wondering what I can do to increase this limit as I already have
options nlp=MSNLP, iterLim=2000, Bratio=1, OptcR = 0, limCol=200000, limrow=1e9, SYSOUT=on, solSlack=1, resLim=9E9 ;

and not all the equations in the model are solved. I need to solve all the equations
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