Search found 162 matches

by bussieck
16 hours ago
Forum: Modeling
Topic: problem with no superbasic variables(simple model)
Replies: 3
Views: 101

Re: problem with no superbasic variables(simple model)

Your solve statement solves the model as an RMINLP (see https://www.gams.com/latest/docs/UG_ModelSolve.html#UG_ModelSolve_model_types). This relaxes the integral requirement. If you solve as MINLP you get: S O L V E S U M M A R Y MODEL beiqi OBJECTIVE z TYPE MINLP DIRECTION MINIMIZE SOLVER COUENNE F...
by bussieck
2 days ago
Forum: Modeling
Topic: problem with no superbasic variables(simple model)
Replies: 3
Views: 101

Re: problem with no superbasic variables(simple model)

You probably solved the non-convex model with a local solver (CONOPT) that gets stuck. The model is small enough to ask a global solver if the model is truly infeasible or if you need to pay more attention in setting a good starting point for your local solver. It turns out the latter is true. I sol...
by bussieck
2 weeks ago
Forum: API
Topic: Setting variable level in Python without using GamsModifier
Replies: 1
Views: 149

Re: Setting variable level in Python without using GamsModifier

It is a bug that the Python API does not recognize your Primal modifier. This has been fixed and will be available in the next maintenance release.

-Michael
by bussieck
2 weeks ago
Forum: Syntax
Topic: gams code for TSP
Replies: 2
Views: 86

Re: gams code for TSP

I guess the message in the log is pretty obvious: --- 102 rows 110 columns 508 non-zeroes --- 90 discrete-columns *** Status: Terminated due to a licensing error *** Inspect listing file for more information If you follow the suggestion in the log and inspect the listing file you find **** THE MODEL...
by bussieck
2 weeks ago
Forum: Syntax
Topic: How to tune the parameter of CPLEX for solving large MIP problem
Replies: 1
Views: 69

Re: How to tune the parameter of CPLEX for solving large MIP problem

The file GAMS/Cplex creates is called 'cplex.op2' including the ticks ('). Remove the ticks in the option to create the file normally, i.e. tuning cplex.op2 . You will find the file in the project directory (IDE) or directory where the main GAMS file resides (Studio). There are cases where the defau...
by bussieck
2 weeks ago
Forum: Modeling
Topic: Incompatible operands for addition error 133.
Replies: 4
Views: 103

Re: Incompatible operands for addition error 133.

I see no compilations error, but the default MINLP solver (DICOPT) has trouble finding a feasible solution. That's not an error. Optimal, unbounded, and infeasible are all valid and good outcomes of an optimization model. In case of a non-convex model you also have to deal with local optima and loca...
by bussieck
2 weeks ago
Forum: Syntax
Topic: How can I change the folder where Gams saves the result.gdx file?
Replies: 1
Views: 59

Re: How can I change the folder where Gams saves the result.gdx file?

Hi depends how you instruct GAMS to create the GDX file. Most commands allow you to specify an absolute or relative path, e.g. execute_unload '..\gdxoutdir\output.gdx';.

-Michael
by bussieck
2 weeks ago
Forum: Modeling
Topic: MIQP Problem Formulated as MIQCP?
Replies: 5
Views: 107

Re: MIQP Problem Formulated as MIQCP?

Unless your norm is something special, this should be written as sigma/2 * sum(eq, sqr(AEG(eg) - AEGhat(eg))).

-Michael
by bussieck
2 weeks ago
Forum: Modeling
Topic: Incompatible operands for addition error 133.
Replies: 4
Views: 103

Re: Incompatible operands for addition error 133.

The code is unclear what z is. Your declare z as a set: Set z Zone the feedstock is located (within 15 30 45 and 60 miles) from the plant /z1*z4/ but then you use it as a variable in equation con_obj(om1).. 1$z(om1) - dir(om1)*sl(om1) =e= rhs(om1); and more obvious in your loop: repeat solve mod_pay...