GAMS World Forum

I suggest that you use the code display feature when pasting GAMS model source (or use the attachment facility). If you paste it as you did e.g. alignments of tables disappear and one has trouble compiling. You can just add "Resul.nw=18 ;" to turn your numbers into fixed format. -Michael

I guess feasOpt trumps iis. Just leave feasOpt out of the option file. If your model is "just" quadratic, convince yourself that you can't formulate in a convex way. Moreover, if you have the quadratic terms only in the objective, you can change the "optimalityTarget" (see https:...

Your runs start from different starting points. In the first case scenarios 2 starts from the manually set starting point while in the second case case it starts from the optimal solution of scenario 1. For NLP (and sometimes for LP) this is a big difference.

-Michael

I don't think there is a "standard". Often paper compare time to solve a model instance. Here the time spend by the solver is the important (modelname.resusd). If the paper is about implementing a more sophisticated algorithm (e.g. decomposition scheme) then the GAMS time should also play ...

The following code should help you: SETS i /1*100/ j 'outputs and inputs' /y, x1, x2/ outp(j) /y/ inp(j) /x1,x2/; Parameter data(i,j); data(i,j) = uniform(0,1); variable obj,x1,x2,dp(i),dn(i); positive variable dp,dn; equation e(i), defobj; set ii(i); e(ii).. data(ii,'y') =e= x1*data(ii,'x1') + x2*d...

Don't worry about the recompile. The BCH programs executed by the solver are always recompiled. This goes super fast. You need to prepare the data from the cuts so you need a cut index. This needs some kind finite number. You made it 10000 but you can increase this but it needs to be defined. Don't...

This is a classic example for piece-wise linear functions. There are many ways to formulate this, see e.g. https://www.gams.com/latest/gamslib_ml/ ... nspwl.html. If your c is bounded, then I would go for the binary formulation (trnsdiscB).

Have fun.

-Michael

24.9 and 25.1 use different versions of Cplex (12.7.1. versus 12.8.0.0). Perhaps a bug was fixed that relates to this behavior. You might want to explore the Cplex' fix list at https://www.ibm.com/support/pages/ilog- ... o-fix-list

-Michael

Can you send a workable small example? -Michael

Hi GAMS Users,

We started distributing GAMS Release 31.1.0 on May 1, 2020.

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

Here are the release notes: https://www.gams.com/latest/docs/RN_31.html

Your GAMS Team
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