Search found 201 matches

by Fred
3 months ago
Forum: Syntax
Topic: Is there a way for GAMS interruption and re-run from where it lasted?
Replies: 6
Views: 437

Re: Is there a way for GAMS interruption and re-run from where it lasted?

You can find the info you need in the documentation: https://www.gams.com/latest/docs/UG_GamsCall.html#GAMSAOsavepoint https://www.gams.com/latest/docs/UG_GDX.html#UG_GDX_EXECUTION_EXECUTE_LOADPOINT Providing a start point to a MIP solver may require to set an extra solver option (see e.g. https://f...
by Fred
3 months ago
Forum: Syntax
Topic: Is there a way for GAMS interruption and re-run from where it lasted?
Replies: 6
Views: 437

Re: Is there a way for GAMS interruption and re-run from where it lasted?

Hi, it seems that you do not want to restart GAMS but a solver run. There is no way to do this. With savepoint you can conveniently store a solution in a gdx file. You could load that solution a a start point the next day but that does not mean that the solver just restarts from the state of second ...
by Fred
3 months ago
Forum: Syntax
Topic: Providing initial solution and reoptimizing
Replies: 3
Views: 296

Re: Providing initial solution and reoptimizing

Nikou,

Dropping fixed values for variables works as you describe it (reste lower/uooer bound).

For MIP solvers, to use a starting point, usually you have to set a corresponding solver option, see e.g. https://www.gams.com/latest/docs/S_CPLE ... EXmipstart

I hope this helps!

Fred
by Fred
3 months ago
Forum: Modeling
Topic: small number safely considered as zero
Replies: 1
Views: 187

Re: small number safely considered as zero

Hi, In Math Programming, strict inequalities (as in your condition X>0) make no sense. For more details see: https://support.gams.com/gams:formulate_a_constraint_with_a_condition Apart from that, I don't see how your single =g= constraint should force y=0 if x>0. Once you know "how much" greater tha...
by Fred
3 months ago
Forum: Modeling
Topic: Questions about the Results
Replies: 4
Views: 456

Re: Questions about the Results

Hi,

It seems that you may have forgotten to add the constraint total_arrival, in which TA occurs, to your model.

I hope this helps!

Fred
by Fred
3 months ago
Forum: Archive Google Group
Topic: Conopt time limit has reached
Replies: 2
Views: 334

Re: Conopt time limit has reached

Hi,

If you want to evaluate GAMS, I suggest to contact sales@gams.com to ask for a time limited evaluation license.

Best,
Fred
by Fred
3 months ago
Forum: API
Topic: pySetup=0
Replies: 1
Views: 834

Re: pySetup=0

Hi Renger,

pySetup is a command line parameter. Just add it to your GAMS call, e.g.

Code: Select all

gams myFile.gms pySetup=0
or in the corresponding fields of Studio/IDE.

I hope this helps!

Fred
by Fred
3 months ago
Forum: Archive Google Group
Topic: Conopt does not give me results for every equation
Replies: 1
Views: 287

Re: Conopt does not give me results for every equation

Could you please elaborate your problem? I don't understand what you mean with Conopt does not give me results for every equation?
Conopt seems to solve just fine when I run your model.

Best,
Fred
by Fred
3 months ago
Forum: Solvers
Topic: Infeasible, but optmal solution found
Replies: 1
Views: 257

Re: Infeasible, but optmal solution found

Hi,

You are looking at the equation listing (https://www.gams.com/latest/docs/UG_GAM ... ionListing) which is part of the model generation output. I.e. the infeasibiities you see refer to the provided start point.

I hope this helps!

Fred
by Fred
3 months ago
Forum: Syntax
Topic: BCH | Cplex | Branch and Cut
Replies: 6
Views: 653

Re: BCH | Cplex | Branch and Cut

Jonathan, It is up to cplex to decide when to use the user cut callback. So it is not surprising that it may not be called between several incumbent checking callbacks. So you are right, with the approach in bchtsp, some cuts may be overwritten before CPLEX adds them to the cut pool. This may not be...