Search found 340 matches

by bussieck
2 months ago
Forum: Syntax
Topic: Minos Run Error
Replies: 2
Views: 304

Re: Minos Run Error

You have specified Cplex options in a Minos option file. Minos does not know what to do with these... Options don't help with models that can be evaluated at bad points. Use bounds to keep the variables away from regions that can't be evaluated, e.g. x.lo=1e-6; for algebra with sqrt(x).

-Michael
by bussieck
2 months ago
Forum: Syntax
Topic: Parameter of Variabe
Replies: 1
Views: 171

Re: Parameter of Variabe

No parameter are know entities. Variables are determined by the solver subject to the equations and the objective.

-Michael
by bussieck
2 months ago
Forum: Syntax
Topic: why is the elapsed seconds smaller than the total seconds
Replies: 1
Views: 99

Re: why is the elapsed seconds smaller than the total seconds

I would not worry about this. This is probably a rounding error in routines that measure time somewhat independently.

-Michael
by bussieck
2 months ago
Forum: Syntax
Topic: use the answer that has been achieved
Replies: 1
Views: 126

Re: use the answer that has been achieved in 2000s in the 7200s running

You can store a solution in a GDX point file (see option savepoint, https://www.gams.com/latest/docs/UG_GamsCall.html#GAMSAOsavepoint). You can load this via execute_loadpoint (https://www.gams.com/latest/docs/UG_GDX.html#UG_GDX_EXECUTION_EXECUTE_LOADPOINT). You also need to tell the solver to start...
by bussieck
2 months ago
Forum: API
Topic: Using Heuristic algorithm in GAMS
Replies: 2
Views: 200

Re: Using Heuristic algorithm in GAMS

GAMS has the solver LocalSolver connected that implements a local search algorithm. If you want to use external algorithms it is relatively easy if your model is simple and can be described by a few sets and parameters: Just export the data to GDX, read it in to Matlab and pass it on to the algorith...
by bussieck
2 months ago
Forum: Tools
Topic: If then statement in Macro
Replies: 2
Views: 182

Re: If then statement in Macro

Instead of putting the 0/1 swap logic in a complicated loop/if structure, you can just use a one-liner parallel assignment statement. But your can also put the parallel assignment or the complicated loop/if logic into a macro: set j/1*10/; parameter c(j); c(j)=uniformInt(0,1); display c; loop(j, if(...
by bussieck
2 months ago
Forum: Syntax
Topic: Euclidean metric
Replies: 1
Views: 83

Re: Euclidean metric

You need to describe your problem better before you can get help here. Read the guidelines of the forum.

-Michael
by bussieck
2 months ago
Forum: Modeling
Topic: Modeling the absolute value
Replies: 23
Views: 6327

Re: Modeling the absolute value

Look at GAMS Model Library model absmip (https://www.gams.com/latest/gamslib_ml/ ... bsmip.html) This shows how to linearly (with discrete variables) model abs, min, max, and sign.

-Michael
by bussieck
2 months ago
Forum: Modeling
Topic: Double Exponent in Objective Function
Replies: 5
Views: 207

Re: Double Exponent in Objective Function

That's a totally different question. If you turn a linear coefficient into a non-linear one this can have all sorts of effects depending on the model, e.g. this want allow the variable to becomes negative. So without specifics it's hard to say what is going on. Why don't you be precise and tell us h...
by bussieck
2 months ago
Forum: Solvers
Topic: solution for GAMS code
Replies: 4
Views: 205

Re: solution for GAMS code

You better know the semantic of your variables and how to produce a solution that makes sense to the user question. Not sure how I can help. Try to be more specific in your question.

-Michael