Search found 198 matches

by Fred
3 weeks ago
Forum: Syntax
Topic: Run a program
Replies: 4
Views: 241

Re: Run a program

What I suggested was a way to get your own license, free of charge, that allows you to solve the model yourself. The license type is called a community license (https://www.gams.com/latest/docs/UG_License.html#GAMS_Community_Licenses). I thought that you would probably prefer being able to solve you...
by Fred
3 weeks ago
Forum: Syntax
Topic: Run a program
Replies: 4
Views: 241

Re: Run a program

Your model fits in the community license limits (https://www.gams.com/latest/docs/UG_Lic ... y_Licenses)
You can contact sales@gams.com to request such a license.

I hope this helps!

Fred
by Fred
4 weeks ago
Forum: Modeling
Topic: Questions about the Results
Replies: 4
Views: 316

Re: Questions about the Results

Actually, the output was right. Your idea of what the output should be like was wrong. Hard to have this fixed by a debugging tool ;-) When facing a problem as the one described in your initial post, it is often a good idea to have a look at the equation listing and column listing to check whether t...
by Fred
4 weeks ago
Forum: Modeling
Topic: Cplex generates optimal solution but then declares it to infeasible
Replies: 3
Views: 266

Re: Cplex generates optimal solution but then declares it to infeasible

Hi Nikou,

Can you share an example, so other forum users can reproduce the observed behavior.
Would also be interesting to know which version you are using.

Best,
Fred
by Fred
1 month ago
Forum: Syntax
Topic: Infeasibilities in loop solve using CPLEX
Replies: 3
Views: 288

Re: Infeasibilities in loop solve using CPLEX

Hi Petros, Happy to read that you solved your problem. However, to avoid confusion, I would like to mention that that the mipstart option has little to do with your initial problem. You wrote that Cplex returns infeasible for your model. Instructing Cplex to use a starting point (which is what you d...
by Fred
1 month ago
Forum: Syntax
Topic: BCH | Cplex | Branch and Cut
Replies: 6
Views: 462

Re: BCH | Cplex | Branch and Cut

Hi Jonathan, To avoid confusion, let's call your first approach "BCH approach" and the second approach "loop approach". I get your idea but there is no such syntax that allows you to do something like =*sense_c(allcuts)*= with the loop approach. The sense_c and rhs_c stuff is designed for the BCH us...
by Fred
1 month ago
Forum: Syntax
Topic: problem with syntax of the equation
Replies: 15
Views: 1416

Re: problem with syntax of the equation

Hi,

You set a lower bound of 0.15 for d(n1 .n5):

Code: Select all

 d.lo(n,np)$a(n,np) = dmin;  
Hence, it cannot be zero.

I hope this helps!

Fred
by Fred
1 month ago
Forum: Syntax
Topic: Is there a way for GAMS interruption and re-run from where it lasted?
Replies: 6
Views: 283

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
1 month ago
Forum: Syntax
Topic: Is there a way for GAMS interruption and re-run from where it lasted?
Replies: 6
Views: 283

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
1 month ago
Forum: Syntax
Topic: Providing initial solution and reoptimizing
Replies: 3
Views: 209

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