Search found 33 matches

by dirkse
1 week ago
Forum: Syntax
Topic: Problem in changing the parameter.
Replies: 6
Views: 161

Re: Problem in changing the parameter.

Luca, If you want an answer to your question, you have only to post a running (and hopefully minimal) example that reproduces the issue. I feel sure this will get you a helpful response. There is also a good chance that putting this together will lead you to the solution of your own problem. -Steve
by dirkse
3 weeks ago
Forum: Modeling
Topic: The shortest Route problem
Replies: 1
Views: 82

Re: The shortest Route problem

Hi, You might think that since the edge weights of a pair-wise shortest-path solution should be 0 or 1 (i.e. the edge is-not or is part of the shortest path) that the variables should be binary, but the LP constraint matrix has some nice properties (I recall learning about totally unimodular matrice...
by dirkse
3 weeks ago
Forum: Modeling
Topic: Error 149, Uncontrolled set entered as constant
Replies: 6
Views: 342

Re: Error 149, Uncontrolled set entered as constant

Sachin, I'm not sure I understand what you are trying to do, but it seems like you want to run a model for a number of different scenarios in the set scn. For each element of scn you will have some different inputs and you'll get (potentially) a different solution. But each solve considers only a si...
by dirkse
1 month ago
Forum: Solvers
Topic: Solver didn't provide marginals for model fulfilment
Replies: 6
Views: 384

Re: Solver didn't provide marginals for model fulfilment

Hi, I can get similar output using the procsel model from the GAMS model library, so I'll use that output as an example. Running with defaults (but ANTIGONE as the solver) I get this in the .lst file: S O L V E S U M M A R Y MODEL process OBJECTIVE pr TYPE MINLP DIRECTION MAXIMIZE SOLVER ANTIGONE FR...
by dirkse
1 month ago
Forum: Solvers
Topic: Solver didn't provide marginals for model fulfilment
Replies: 6
Views: 384

Re: Solver didn't provide marginals for model fulfilment

The model status of 8 Integer Solution indicates that the solver has found an integer solution, but it is not making the stronger claim that it is the globally optimal solution. This is somewhat at odds with the message "Termination status: Global minimum." that you have in your note. Without seeing...
by dirkse
1 month ago
Forum: Solvers
Topic: Solver didn't provide marginals for model fulfilment
Replies: 6
Views: 384

Re: Solver didn't provide marginals for model fulfilment

Hello lixlz51, Your post raised some questions. First, you don't say anything about yourself (name, affiliation, etc.) This forum isn't intended for anonymous usage. Second, what do you mean by "model fulfillment"? What is it you would do with the marginal values (for a MINLP) that BARON might retur...
by dirkse
1 month ago
Forum: API
Topic: Python API - Solver Statusthon API - Solver Status
Replies: 1
Views: 200

Re: Python API - Solver Statusthon API - Solver Status

Mostafa, Your GAMS source contains two models, and yet you ask for the flag that indicates if the model is infeasible. What model do you mean? In general, GAMS does not return a code or status about any model, even if there is only one such in the GAMS source. The usual thing to do is create whateve...
by dirkse
2 months ago
Forum: Modeling
Topic: How to compute endogenous cost expressions in GAMs
Replies: 3
Views: 237

Re: How to compute endogenous cost expressions in GAMs

Hi, GAMS ships with stolib, an extrinsic function library full of functions relevant to probability and statistics. For example, the CDF and inverse-CDF functions for many distributions (including the normal distribution) are contained in this library. Details and examples are in the docs: https://w...
by dirkse
2 months ago
Forum: Modeling
Topic: GAMS does not read my code
Replies: 8
Views: 258

Re: GAMS does not read my code

Your problem is similar to that of accessing all elements of a parameter A(i,i). This link explains how an alias (or in your case, two aliases: one for i, another for j) will solve the problem: