Applying cplex options in GAMS for out of memory

GAMS
1

I am working on an cplex mip model in GAMS and have recently had the error of “insufficient memory”.

I am running the same model twice, one where all variable are free, and one where I attempt to fix some variables in order to compare with historical data. The “free” model runs great (in 30 seconds) but as soon as I constrain the variables, I run out of memory after about 10 minutes.

I am thus trying to apply some cplex options to force GAMS to act differently. However GAMS does not understand when I try to apply the options and gives me an error.

This is what I have tried:

laurenmodel.optfile = 1 ;
$onecho > cplex.opt
nodefileind 3
varsel 3
$offecho

This is the error:

Error 140. Unknown symbol.

GAMS doesn’t like “optfile”.

How can I make it so that GAMS understands the cplex options?

Thanks

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2

Dear Lauren,

You need to make a file called “cplex.opt”, put the options like nodefileind and varsel in that file and save it in the directory “projdir”, of the directory where you installed GAMS.

Kind regards,
Henry Vermue

On Friday, February 15, 2013 5:47:04 PM UTC+1, Lauren Cook wrote:

I am working on an cplex mip model in GAMS and have recently had the error of “insufficient memory”.

I am running the same model twice, one where all variable are free, and one where I attempt to fix some variables in order to compare with historical data. The “free” model runs great (in 30 seconds) but as soon as I constrain the variables, I run out of memory after about 10 minutes.

I am thus trying to apply some cplex options to force GAMS to act differently. However GAMS does not understand when I try to apply the options and gives me an error.

This is what I have tried:

laurenmodel.optfile = 1 ;
$onecho > cplex.opt
nodefileind 3
varsel 3
$offecho

This is the error:

Error 140. Unknown symbol.

GAMS doesn’t like “optfile”.

How can I make it so that GAMS understands the cplex options?

Thanks

–
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