GAMS World Forum

You have a Mac with an M1 or M2 chip but the GAMS 34 distribution is Intel only. So you would need an Intel Python running under Rosetta 2 on you machine. The native M1/M2 port for GAMS was introduced with GAMS 43 (see https://www.gams.com/latest/docs/RN_43.html#g4310_PLATFORMS). So many good reason...

You don't have a bi-level optimization problem. You have a two-stage stochastic program! The GAMS compiler gives you good help: 171 solve project max z use EMP scenario dict; **** $790,257 **** 257 Solve statement not checked because of previous errors **** 790 Symbol dimension mismatch **** The fol...

and it starts reporting solutions, which I've interpreted, rightly or wrongly, as the model finding solutions with the same objective value. This is wrongly assumed. If you would have send the entire width of the log I could have shown you the difference in incumbent values. With what you sent I ca...

Not clear what problem you describe. When I run the model you uploaded I get: --- Scenario s0: Records read: 4650 --- Solution statistics for scenario s0 --- Unmatched Records 0 --- Solver Status 1 Normal Completion --- Model Status 1 Optimal --- Objective Value 2.80346e+09 --- Resource Usage 281.79...

Hi ,not sure I understand everything what you write here. Degeneracy usually means (see https://glossary.informs.org/second.php?page=D.html#Degeneracy) that we have multiple solution of the same value. You describe that Cplex "always identifies several hundred solutions prior to solving". ...

UCM_h.log This all looks very much like the cluster is killing your jobs. GAMS runs the solver as an executable (communicating the model instance via scratch files) so even if the solver dies, the GAMS job should nicely continue and write proper lst files. Since this does not happen (and since the ...

In order to run this, we would need a GDX file. Can you supply one? Moreover, the export to Excel can be improved (performance). Rather than calling gdxxrw for each variable/parameter, you can create (at compile $on/offEcho or execution time $on/offPut) a gdxxrw instruction file: $if not %PrintResul...

What does "System limits" actually refers to in this context ? GAMS has some internal limits, e.g. the number of variables a model can have <2.1e9 and other limits. This is what this return code means. I am a little surprised that the log did not give you more information on what limit wa...

Sebastian,

On professional development. I can recommend Bruce McCarl's GAMS classes. He starts one next week. See https://www.gams.com/courses/.

-Michael

Not sure where you picked upo the idea to terminate the gdxxrw instructions with a semicolon (dset=i rng=Datos!B5 rDIM=1 ; ). With that gdxxrw tries to interprete 1; as a number and fails. Reading parameters requires reading and index and the numbers. With the instructions "par=Qfvmax rng=Datos...