Search found 1042 matches
- 7 years ago
- Forum: Solvers
- Topic: cplex unable to load name
- Replies: 0
- Views: 5164
Re: cplex unable to load name
Hmmm, there can be a few reasons why the loading of the names fails. First you might have disabled the generation of names inside the GAMS code. One can do this by setting mymodel.dictfile=0; before the solve statement (https://www.gams.com/latest/docs/userguides/mccarl/model_attributes_mainly_used_...
- 7 years ago
- Forum: Modeling
- Topic: how to generate lp file without solving it
- Replies: 0
- Views: 10987
Re: how to generate lp file without solving it
Hi, I don't know what kind of debugging you want to do but usually the equation listing in the listing file is a pretty good debugging tool if you visually need to inspect your constraints: A Transportation Problem (TRNSPORT,SEQ=1) Equation Listing SOLVE transport Using LP From line 66 ---- cost =E=...
- 7 years ago
- Forum: Solvers
- Topic: Multiobjective optimization
- Replies: 1
- Views: 4544
Re: Multiobjective optimization
Your analysis is correct. For other readers, this is only for the GAMS/Gurobi solver. Anyhow, in case of "MultiObj=1" the coefficients in the master objective "just" help to build the different priority classes. When I implemented this, I had in mind that I wanted to go easily fr...
- 7 years ago
- Forum: Solvers
- Topic: Problems with the initial point
- Replies: 4
- Views: 6524
Re: Problems with the initial point
Tiago, I agree that we should make sys12 more visible and give it a better name, but I also believe that this is a good default. Even global solvers benefit from a good starting point because they use local solvers for local search (e.g. BARON does a multi-start based on the initial point that hopef...
- 7 years ago
- Forum: Solvers
- Topic: CPLEX LP Warmstart
- Replies: 3
- Views: 6055
Re: CPLEX LP Warmstart
It does not matter where the basis (complete or incomplete) comes from. You just need to set (.l and) .m of your variables and equations. I did not get the experiment you tried to do in your attached GAMS model. To me it looks like that the second solve successfully restarted from a basis.
-Michael
-Michael
- 7 years ago
- Forum: Solvers
- Topic: CPLEX stuck "Removing shift" on MILP
- Replies: 3
- Views: 5170
Re: CPLEX stuck "Removing shift" on MILP
This truly looks like a Cplex bug or numerical issue. If you add options writesav prob.sav writeparam param.prm to your GAMS/Cplex option file you could submit these two files together with the entire log to support@gams.com or directly to the Cplex folks. Please also provide information about the p...
- 7 years ago
- Forum: Solvers
- Topic: Problems with the initial point
- Replies: 4
- Views: 6524
Re: Problems with the initial point
Local NLP solvers need a good starting point to improve on. The starting point you provide (0,0) can't be evaluated and hence the solver could not compute a direction that improves the situation. Hence GAMS checks if the starting point can be calculated. If not, GAMS will not pass the model to the s...
- 7 years ago
- Forum: Bugs
- Topic: Gams does not print solution when click "Interrupt" on windows 10
- Replies: 1
- Views: 8258
Re: Gams does not print solution when click "Interrupt" on windows 10
The problem is that GAMS waits for the user to react on the "Terminate batch job (Y/N)?". With older OS versions this was not a problem but it surfaced eventually. Anyhow, a newer GAMS version (>=24.0) fixes this problem (see http://www.gams.com/latest/docs/releasenotes/24.0.html#gams). Yo...
- 7 years ago
- Forum: Solvers
- Topic: CPLEX LP Warmstart
- Replies: 3
- Views: 6055
Re: CPLEX LP Warmstart
Leo,
The key GAMS/Cplex option for LP restarts is 'advind' (http://www.gams.com/latest/docs/solvers ... PLEXadvind). Perhaps you can post some logs or even share your model and starting point, so we have more to go on.
-Michael
The key GAMS/Cplex option for LP restarts is 'advind' (http://www.gams.com/latest/docs/solvers ... PLEXadvind). Perhaps you can post some logs or even share your model and starting point, so we have more to go on.
-Michael
- 7 years ago
- Forum: Tools
- Topic: Saving solution with partial solve, and restarting solve
- Replies: 2
- Views: 4820
Re: Saving solution with partial solve, and restarting solve
Restarting an LP solver from a previous basis used to be easy and reliable 20 years ago. We even had some tests that for this. With modern LP solvers this is not necessarily the case anymore, let along MIP solvers. Very often you have to decide to a) start from an advanced basis and not do presolve ...