GAMS World Forum

If you need the previous "period" in your model, you should think in terms single dimension time periods rather than (y,d,t) tuples and model with this. If you need occasionally access to data of a particular year, date, hour of a period you can do this by mapping from the period to the y,...

This is a straight forward text book optimization problem. Get the math straight and GAMS will follow. If you have detailed questions on how to to particular formulations or tasks in GAMS you will find answers here. Getting the math right is the whole fun and you should not shortcut this experience....

What i should GAMS use for the s(i)? The control of i stops with the sum. The equation is controlled over j.

-Michael

Not sure what editor you used, but GAMS does not like your "≤" nor the "∗". These are unicode characters not part of the GAMS language, hence the compiler gets confused. Just use the regular ASCII characters/character sequence "<=" and "*".

-Michael

No, the "$if set" only works on a single compile time variable name, not an expression. You can work around this by having a parallel set of numerical compile time variables and then use $ifThenE: $set xset 0 $if set x $set xset 1 $set yset 0 $if set y $set yset 1 $log %xset%%yset% $ifThen...

Hi GAMS Users,

We started distributing GAMS Release 46.1.0 on February 21, 2024.

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

Here are the release notes: https://www.gams.com/latest/docs/RN_46.html

Your GAMS Team
www.gams.com

Hi GAMS Users, We would like to announce the availability of the GAMS Beta Release 46.0.0. Please consult the beta release notes for details about new features and updated solvers: https://www.gams.com/beta/docs/RN_46.html If you are interested in experimenting with this beta release, please downloa...

BARON only "understands" a subset of functions offered by GAMS. BARON, unlike local solvers like Conopt, need the algebra of the non-linear expression to build (linear) underestimators. It can do that for all operators (*,/,**,+,-) but not for all functions. The trig functions sin, cos, ta...

GAMS defines the membership of a variable to a SOS set by the last index in the SOS variable declaration. As a consequence of this you can't have a variable appear in two SOS sets. Your model has this (e.g. W(T2,2,U1) shows up in the first and second SOS set in your example). I have not seen models ...

In an LP there is no such thing as bounds on the dual. It is not unusal to get different dual solution with different solvers. With LPs you can have different optimal basis with different (primal and) dual solutions. Uniqueness in the optimal solution is very rare in practical models. If you want mo...