Search found 179 matches

by Fred
1 month ago
Forum: Solvers
Topic: Global Optimal in GAMS Solvers (CPLEX and BARON)
Replies: 6
Views: 440

Re: Global Optimal in GAMS Solvers (CPLEX and BARON)

Hi, The "best bound" column in the CPLEX log refers to the best bound that is known so far. Look for example at the following excerpt of a CPLEX log for a maximization problem. Nodes Cuts/ Node Left Objective IInf Best Integer Best Bound ItCnt Gap 0 0 29.5688 108 29.5688 157 [...] * 0+ 0 8.0000 26.3...
by Fred
1 month ago
Forum: Solvers
Topic: Global Optimal in GAMS Solvers (CPLEX and BARON)
Replies: 6
Views: 440

Re: Global Optimal in GAMS Solvers (CPLEX and BARON)

Hi,

"best possible" refers to the value of the best bound on the objective function value.

I hope this helps!

Fred
by Fred
1 month ago
Forum: Solvers
Topic: Global Optimal in GAMS Solvers (CPLEX and BARON)
Replies: 6
Views: 440

Re: Global Optimal in GAMS Solvers (CPLEX and BARON)

1- I have an Integer Linear programming problem I solved it using CPLEX solver (mip) with optcr=0 does this provide a local optimal solution or global solution? A global optimal solution. If a use BARON (mip) instead will it be able to provide the global optimal solution as it is a deterministic gl...
by Fred
1 month ago
Forum: Modeling
Topic: Problem with endogenous variable
Replies: 1
Views: 139

Re: Problem with endogenous variable

Hi,

Not sure how your model is related to the marco model from the library (it looks very different).
In equation BlendingProperties you multiply variables

Code: Select all

ComponentProperty(component, specs) * Blend(final, component)
. So your model is definitely not linear.

I hope this helps!

Fred
by Fred
1 month ago
Forum: Modeling
Topic: Generation time takes too long
Replies: 4
Views: 243

Re: Generation time takes too long

Hi,

To provide help it would be good to be able to reproduce the observed behavior. Maybe you can share the missing include files?

Best,
Fred
by Fred
1 month ago
Forum: Syntax
Topic: Missing -ve sign during equation formulation in .lst file
Replies: 7
Views: 283

Re: Missing -ve sign during equation formulation in .lst file

roys wrote:
1 month ago
[...]why my objective function is negative when all its constituents bear a positive value.
Your lst file shows that many of the constituents of the objective function do not bear a positive value.

I hope this helps!

Fred
by Fred
1 month ago
Forum: Syntax
Topic: Missing -ve sign during equation formulation in .lst file
Replies: 7
Views: 283

Re: Missing -ve sign during equation formulation in .lst file

Hi, I cannot reproduce your findings. The equation listing shows ---- OBJECTIVE =E= OBJECTIVE.. PRODCOST - PRODCOST_BY_INTERVAL(7) - PRODCOST_BY_INTERVAL(1) - [...] - PRODCOST_BY_INTERVAL(167) - PRODCOST_BY_INTERVAL(168) =E= 0 ; (LHS = 0) Are you sure that the lst excerpt Trial2_lst.txt from your in...
by Fred
1 month ago
Forum: Modeling
Topic: Linking Macro and Micro Periods (Sets)
Replies: 1
Views: 109

Re: Linking Macro and Micro Periods (Sets)

Hi Eric,

You might want to read about multi-dimensional sets (https://www.gams.com/latest/docs/UG_Set ... sionalSets) to figure out how to implement a mapping between your sets t and s.

I hope this helps!

Fred
by Fred
1 month ago
Forum: Modeling
Topic: Solve aborted, Execerror = 141
Replies: 1
Views: 98

Re: Solve aborted, Execerror = 141

Hi,

Did you look at the lst file? It usually provides meaningful error messages (search for ****).
It might help, if you share your code, so other forum users can reproduce the issue.

Best,
Fred
by Fred
1 month ago
Forum: Syntax
Topic: Missing -ve sign during equation formulation in .lst file
Replies: 7
Views: 283

Re: Missing -ve sign during equation formulation in .lst file

Hi,

Could you share the GDX files such that one could actually run the gms file to reproduce this?

Best,
Fred