Search found 214 matches

by dirkse
5 months ago
Forum: Solvers
Topic: Duality Gap
Replies: 2
Views: 6039

Re: Duality Gap

Hello,

I believe that the helpful users in this forum will be more inclined to offer help and better able to offer help if you follow the forum rules:

app.php/rules

BTW, the rules don't mention sending a log file, but in this case it seems like a good idea.

-Steve
by dirkse
5 months ago
Forum: Syntax
Topic: problem in using ord
Replies: 1
Views: 6331

Re: problem in using ord

Sajjad, In the example below are a couple ways to do what you ask. set i / 1*3 /; singleton set s(i); scalar counter / 1 / a / NA / b / NA / ; parameter dinf(i); dinf(i) = ord(i); a = sum{i$[ord(i) = counter], dinf(i)}; * singleton sets can have at most one member, so * we can do things with them we...
by dirkse
5 months ago
Forum: Syntax
Topic: How to terminate mpec sooner
Replies: 1
Views: 8257

Re: How to terminate mpec sooner

T_k, If you are solving your MPEC model with the NLPEC solver, than you are ultimately running a DNLP solver on a reformulated version of the problem. So the answer depends entirely on what DNLP solver you are using. Please specify. Many DNLP solvers are local solvers, i.e. they are looking for a po...
by dirkse
6 months ago
Forum: Bugs
Topic: Out of memory problem
Replies: 5
Views: 4555

Re: Out of memory problem

Wenkey, I think you have misunderstood the workfactor option: https://www.gams.com/44/docs/UG_GamsCall.html#GAMSAOworkfactor The value of 1 is the default. Anything larger than one grows the workspace used by CONOPT. 2 is a reasonable value to try. 10 is fairly aggressive. 1e299 is not reasonable. H...
by dirkse
6 months ago
Forum: Syntax
Topic: Changing location for lst files
Replies: 3
Views: 9037

Re: Changing location for lst files

Hello,

Perhaps you want to also try the workdir parameter: it might be helpful if you want to redirect many things at once.

https://www.gams.com/44/docs/UG_GamsCal ... SAOworkdir

For example do:
mkdir foo
( cd foo ; gamslib trnsport )
gams trnsport workdir=foo lo=4
ls foo

HTH,

-Steve
by dirkse
7 months ago
Forum: Modeling
Topic: arrangement of LHS and RHS in equality equations (MCP)
Replies: 2
Views: 5198

Re: arrangement of LHS and RHS in equality equations (MCP)

Tatjana, You are asking some good questions here, questions that get to the foundations of what an MCP model really is. Fundamentally, MCP is not about equations and inequalities. It is about function-variable pairs, and the relationships dictated by those pairs. I could say a lot here, but it would...
by dirkse
8 months ago
Forum: Modeling
Topic: use of subset
Replies: 4
Views: 4144

Re: use of subset

Zorro, I encourage you to look at the GAMS model library: anywhere is probably useful, but start with the trnsport and dice models if you don't have other ideas. You will observe that using multiply-indexed variables is the normal practice. There is nothing unprofessional about this. It is very much...
by dirkse
8 months ago
Forum: Syntax
Topic: JAMS Pre processing failed
Replies: 5
Views: 9373

Re: JAMS Pre processing failed

Omar,

This seems like a trick question. The solve statement does not include any equations. For example:

Code: Select all

solve myMod using emp min z;
contains no equations and only one variable.

-Steve
by dirkse
8 months ago
Forum: Syntax
Topic: JAMS Pre processing failed
Replies: 5
Views: 9373

Re: JAMS Pre processing failed

Hello, You are getting closer. Have a look at the transbp model in EMPLIB: it demonstrates the use of indexed equation and variable symbols in the EMP info file. The EMP info file in that example looks like this: bilevel min z x cost supply demand vi extdem g with no index sets with the equation and...
by dirkse
8 months ago
Forum: Syntax
Topic: JAMS Pre processing failed
Replies: 5
Views: 9373

Re: JAMS Pre processing failed

Hello, Your EMP info file is not proper. It must start with a keyword, not a variable or equation name. In the docs for bilevel models there are two examples (bard511 and ccmg71). https://gams.com/latest/docs/S_JAMS.html#EMP_BILEVEL_PROGRAMS Each example includes a link to the complete model in the ...