Search found 1049 matches

by bussieck
11 months ago
Forum: Solvers
Topic: BARON: terminates solver when solution does not improve after x amount of time
Replies: 1
Views: 7647

Re: BARON: terminates solver when solution does not improve after x amount of time

Not with BARON. Some solvers allow you "user defined" termination via callbacks and this is made available to GAMS users, see e.g. https://www.gams.com/latest/docs/S_CPLE ... ipstopexpr.

-Michael
by bussieck
11 months ago
Forum: Modeling
Topic: Problem infeasible or unbounded
Replies: 1
Views: 3375

Re: Problem infeasible or unbounded

Nothing. You should use code boxes for your model and output though. You model in unbounded. Just limit the objective variable (e.g. z.lo = -1e6;) and see what "run away" variables you get. Check your application why this should not happen, turn your insight into constraints/model logic. -...
by bussieck
11 months ago
Forum: Syntax
Topic: dimension error
Replies: 5
Views: 9465

Re: dimension error

The attached program succeeds without a problem. If I remove the $stop and let GAMS continue, I get compilation errors when compiling "startup(s*,i,t)", you probably means "startup(s,t,*,i)" at least that makes sense from the code you have later. Now after fixing all this, I get ...
by bussieck
11 months ago
Forum: Syntax
Topic: dimension error
Replies: 5
Views: 9465

Re: dimension error

Don't just paste your GAMS source as normal text. There are fine code boxes in the forum editor. Also this issue is related to data so upload your Excel and GDX file as well so one can reproduce the error.

-Michael
by bussieck
11 months ago
Forum: Modeling
Topic: How do I formulate logical expressions in equations with variables??
Replies: 4
Views: 5008

Re: How do I formulate logical expressions in equations with variables??

Look for logic equations in the forum. It is a frequently asked questions.

-Michael
by bussieck
1 year ago
Forum: Syntax
Topic: Loading data from Excel Sheet into GAMS
Replies: 4
Views: 8340

Re: Loading data from Excel Sheet into GAMS

Please read the documentation of gdxxrw at https://www.gams.com/latest/docs/T_GDXXRW.html. All parameters are read with the index k and the value of the parameter in the neighboring cell. Your sheets don't mention the index (k) at all. You did not provide the elements of set k, but here I am assumin...
by bussieck
1 year ago
Forum: Modeling
Topic: Assistance with conditional non-equals
Replies: 4
Views: 3134

Re: Assistance with conditional non-equals

I see. Debugging models is hard. What you need to do is to take be "better" solution you get by just providing the .l (or leave this out because it has no effect) and look at this solution. Explain the solution to yourself and detect the flaws in this solution. Next look at the equation th...
by bussieck
1 year ago
Forum: Syntax
Topic: Dimension Different Error (electricity pricing model)
Replies: 2
Views: 6482

Re: Dimension Different Error (electricity pricing model)

I think you need to upload something that lets us reproduce the error. I can't do this from the code snippets you have pasted.

-Michael
by bussieck
1 year ago
Forum: Syntax
Topic: Loading data from Excel Sheet into GAMS
Replies: 4
Views: 8340

Re: Loading data from Excel Sheet into GAMS

Sure, if you provide the Excel files to see what's going on.

-Michael