Search found 11 matches
- 4 years ago
- Forum: Solvers
- Topic: Different results with zero optimality gap: MIP against SOS2
- Replies: 2
- Views: 3378
Re: Different results with zero optimality gap: MIP against SOS2
Many thanks for your attention. The original problem is non-convex with many local solutions. However, with a piecewise linearization technique, the approximate equivalent MILP model is built which is convex in the relaxed form (relaxing integer values). Consequently, it is expected that all MILP so...
- 4 years ago
- Forum: Solvers
- Topic: Different results with zero optimality gap: MIP against SOS2
- Replies: 2
- Views: 3378
Different results with zero optimality gap: MIP against SOS2
Different results with zero optimality gap: MIP against SOS2 Dear all I have a MIP model with some SOS2 constraints. I implement the SOS2 constraints with two approaches including SOS2 variable definition in GAMS, i.e. native SOS2 provided by CPLEX, and a MIP technique enforcing SOS2 constraints usi...
- 4 years ago
- Forum: Modeling
- Topic: How to implement integration in objective function of a model
- Replies: 0
- Views: 1988
How to implement integration in objective function of a model
Dear all I am trying to minimize area between two curves using numerical integration by trapezoidal rule. The integral bounds are also variables in my model, i.e. int(f(x),[a , b]) wherein a and b are variables representing integral bounds. Any idea for formulation of the model is appreciated. Thank...
- 4 years ago
- Forum: Solvers
- Topic: Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
- Replies: 2
- Views: 3215
Re: Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
Hi, Thank you once again. But I could not implement the method. Certainly my CPLEX does not include miptrace maybe because of using older version of GAMS, i.e. 24.1. The provided file in following link also did not helped. Advanced Use of GAMS Solver Links: https://old.gams.com/presentations/present...
- 4 years ago
- Forum: Modeling
- Topic: Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
- Replies: 2
- Views: 2252
Re: Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
Hi,
Thanks. But I can not find it in doc/solver/CPLEX maybe because of using GAMS 24.1.
Best regards;
Hossein
Thanks. But I can not find it in doc/solver/CPLEX maybe because of using GAMS 24.1.
Best regards;
Hossein
- 4 years ago
- Forum: Solvers
- Topic: Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
- Replies: 2
- Views: 3215
Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
Dear all
I want to record some outputs generated by CPLEX such as the iteration number, objective and the associated time so that I can plot some convergence characteristic, for example objective-iteration number, objective-time and objective-number of nodes.
Have you any idea?
Best regards;
Hossein
I want to record some outputs generated by CPLEX such as the iteration number, objective and the associated time so that I can plot some convergence characteristic, for example objective-iteration number, objective-time and objective-number of nodes.
Have you any idea?
Best regards;
Hossein
- 4 years ago
- Forum: Modeling
- Topic: Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
- Replies: 2
- Views: 2252
Saving some iteration log data generated by CPLEX, as a MIP solver, into parameters. Is this possible?
Dear all I want to record some outputs generated by CPLEX such as the iteration number, objective and the associated time so that I can plot some convergence characteristic, for example objective-iteration number, objective-time and objective-number of nodes. Have you any idea? Best regards; Hossein
- 4 years ago
- Forum: Modeling
- Topic: Increasing ‘reslim’ but weaker result in a mip solver
- Replies: 5
- Views: 3666
Re: Increasing ‘reslim’ but weaker result in a mip solver
Dear Fred
Many thanks for taking the time and effort in answering this post.
Best regards;
Hossein
Many thanks for taking the time and effort in answering this post.
Best regards;
Hossein
- 4 years ago
- Forum: Modeling
- Topic: Increasing ‘reslim’ but weaker result in a mip solver
- Replies: 5
- Views: 3666
Re: Increasing ‘reslim’ but weaker result in a mip solver
Many thanks for your quick answer. The model is minimizing problem. I didn’t mean that the solutions with reslim=300 always are better than ones with reslim=600. Actually, the obtained results usually oscillate between two or three objective values for the both reslims. I did my best to keep everyth...
- 4 years ago
- Forum: Modeling
- Topic: Increasing ‘reslim’ but weaker result in a mip solver
- Replies: 5
- Views: 3666
Increasing ‘reslim’ but weaker result in a mip solver
Dear all I am solving a MILP model using CPLEX as a solver. I increase the ‘reslim’ to enhance the solution and reduce the optimality gap. But sometimes increasing the ‘reslim’ leads to worse objective. Initially I guessed that probably it is because of different CPU and/or RAM amount engaged by ope...