GAMS World Forum

Hi GAMS Users,

We started distributing GAMS Release 45.1.0 on October 17, 2023.

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

Here are the release notes: https://www.gams.com/latest/docs/RN_45.html

Your GAMS Team
www.gams.com

Hi GAMS Users, We would like to announce the availability of the GAMS Beta Release 45.0.0. Please consult the beta release notes for details about new features and updated solvers: https://www.gams.com/beta/docs/RN_45.html If you are interested in experimenting with this beta release, please downloa...

There is a somewhat simpler example: cta (https://www.gams.com/latest/gamslib_ml/ ... b_cta.html) which essentially cuts away the optimal solution a couple of time to get suboptimal solutions. -Michael

Look at a TSP example (https://www.gams.com/latest/gamslib_ml/ ... _tsp1.html) in the GAMS model library where a sub-tour elimination constraint gets added in every iteration. You will need to overestimate the number of iterations (cc) and use a loop though. Good luck.

-Michael

The error message is slightly misleading, it probably failed because the model you want to solve is too big for the community license. See https://www.gams.com/latest/docs/UG_License.html#UG_License_Additional_Solver_Limits for the model size limits for the community license. BARON has tighter limit...

The listing file points you nicely to the issue and gives a reasonable explanation "Incompatible operands for relational operator": 95 inventoryBalance(p,s,t).. 96 I(t,p,s) =e= I(t-1,p,s) + X(t,p,s) - sum(s_1$(s_1 = sPrec(p,s) and s_1<>s), X(t-rt(s,s_1),p,s_1)*a(p,s)) - d(t,p,s); **** $148...

The optgams.def file is a file to let e.g. Studio know what options GAMS accepts and what their default values are. The GAMS documentation never had anything on adjusting the file. It is for pure internal use and editing might have some unexpected results.

-Michael

Why do you expect the ratio to be stable? Many optimization problems are degenerate, i.e. with the same objective function you have many solutions. Which one the solver spits out is a matter of chance. So if you change the input (e.g. different bounds) the solver takes a slightly different path and ...

The solver tells you the model is infeasible. There are many tools to analyze infeasibility. Infeasibility is a normal state for a mathematical program (besides optimal and unbounded). There are tools (e.g. iis or feasopt) that help you pinpoint the cause for the infeasibility. Search the forum for ...

Make "set li /li0*li40/;" and then a dynamic "set lirun(li);". Declare all symbols over li but when you use the symbol index over lirun. Now first you assign only li4 to lirun (lirun('li4')=yes; solve ..." and then you solve for all li: lirun(li) = yes; solve ...". -Mic...