GAMS World Forum

Performance degradation of the size has probably little to do with your old vs. new hardware. I would carefully compare the logs of the runs on the new and old machine and see where they start to differ. I doubt that they are identical (other than different times). I guess on the new machine somethi...

Hi GAMS Users,

We started distributing GAMS Minor Release 38.2.0 on February 17, 2022.

You can download the software from https://www.gams.com/download/

Here are the release notes: https://www.gams.com/latest/docs/RN_38.html#RN_3820

Your GAMS Team
www.gams.com

Conopt does not solve models with binary variables. -Michael

Cplex is in good company. Gurobi has no solution after almost 30 minutes: Nodes | Current Node | Objective Bounds | Work Expl Unexpl | Obj Depth IntInf | Incumbent BestBd Gap | It/Node Time ... 118 120 1.4104e+08 107 4814 - 1.4104e+08 - 624 1685s 119 121 1.4104e+08 108 4217 - 1.4104e+08 - 799 1693s ...

There is no GAMS option for this. This is solver specific. Check the solver documentation of the used solved and set the option (if available). For example, for GAMS/Cplex this option is called epint . For most solvers the default is 1e-6 and is usually good enough. Reducing this option (e.g. epint)...

BARON can prove global optimality for non-convex models. DICOPT guarantees global optimality only for convex models and is a heuristic for non-convex problem which provides you hopefully with a good solution. It seems that your model falls into the non-convex category, hence you can't get what you w...

Hi, Having a script to execute is key when you do performance analysis. I transformed your description and loop code into a model where I can easily change the size of the g and ay sets. I also have some code to generate random data for arbitrary sized instances (this code itself does not execute th...

If I understand you correctly you want to vary the rho and eta from the table coefs for Asia, Europe, America, and China and rerun the model: Table coefs(n,*) 'demand and supply data' alpha cap beta rho eta Asia 0 762.667 7.198010732 Europe 0 0 762.667 12.47749089 Americas 0 0 762.667 88.68732678 Ch...

If you need to tell Conopt to accept coefficients/gradients of 1e30 (Rtmaxv=10e29) you have a very poorly scaled model. If you scale your model properly I guess your infeasibility problems (due to scaling) will go away. The Conopt manual has a good section on scaling: https://www.gams.com/latest/doc...

Not many solvers released an arm-based library so far. If/When this picks up we will also provide a arm-based distribution.

-Michael