Search found 1042 matches
- 2 years ago
- Forum: Modeling
- Topic: Testing a multi-objective optimization algorithm with uf1 problem
- Replies: 1
- Views: 1116
Re: Testing a multi-objective optimization algorithm with uf1 problem
If this is your UF1 image.png then obviously with x1 in [0,1] and xj in [-1,1] there is no chance in getting a negative value for f1 or f2. If you have negative values you probably made a mistake. Did you check the model status (for feasible solution)? It would help if you post some source. -Michael
- 2 years ago
- Forum: Solvers
- Topic: IPOPT EXIT: Solved To Acceptable Level.
- Replies: 3
- Views: 7021
Re: IPOPT EXIT: Solved To Acceptable Level.
The GAMS/IPOPT link has to map any of the IPOPT internal status (e.g. Solved To Acceptable Level ) to a combination given in the list of GAMS' model and solve status, GAMS support many solvers so all solvers need to map into the GAMS status world. Now see how the GAMS/IPOPT link maps Solved To Accep...
- 2 years ago
- Forum: Solvers
- Topic: IPOPT scaling
- Replies: 1
- Views: 2654
Re: IPOPT scaling
You should find out why IPOPT can't evaluate the input point. Some solvers don't like gradients that are too large. Usually GAMS already complains if you have a truly bad input point that can't be evaluated (at least for the function evaluation and to some extent for the gradient). IPOPT works also ...
- 2 years ago
- Forum: Solvers
- Topic: IPOPT EXIT: Solved To Acceptable Level.
- Replies: 3
- Views: 7021
Re: IPOPT EXIT: Solved To Acceptable Level.
The GAMS/IPOPT link maps this status to some combination of model and solve status, see https://www.gams.com/38/docs/UG_GamsCall.html#GAMSAOmodelstat and https://www.gams.com/38/docs/UG_GamsCall.html#GAMSAOsolvestat. You should check if this combination is any different than with the other solves an...
- 2 years ago
- Forum: Syntax
- Topic: Binary variables
- Replies: 5
- Views: 8014
Re: Binary variables
As all solvers SBB has a tolerance for what it considers to be integer, see https://www.gams.com/38/docs/S_SBB.html#SBBepint. The default for epint is at 1e-5. So if abs(round(x)-x)<epint x does not need to be branched on. You can change the tolerance within a solver option file.
-Michael
-Michael
- 2 years ago
- Forum: Solvers
- Topic: Elimination constraint & subset usage
- Replies: 1
- Views: 2594
Re: Elimination constraint & subset usage
Either use the compact Miller, Tucker and Zemlin formulation to avoid subtours or build up only the necessary subtour elimination constraints. Both are done here: https://www.gams.com/latest/gamslib_ml/ ... _tsp5.html
-Michael
-Michael
- 2 years ago
- Forum: API
- Topic: Running NEOS from Python API , importing data from excel
- Replies: 1
- Views: 5337
- 2 years ago
- Forum: Syntax
- Topic: Running NEOS from Python API
- Replies: 7
- Views: 8092
Re: Running NEOS from Python API
NEOS does not allow you to run external programs like gdxxrw, so do the Excel to GDX conversion locally and submit gms and gdx to NEOS.
-Michael
-Michael
- 2 years ago
- Forum: Syntax
- Topic: Parameter Syntax with "#" sign and 3 Dimensions
- Replies: 3
- Views: 2090
Re: Parameter Syntax with "#" sign and 3 Dimensions
The srep parameter always depends on the scenarios only. It gives information about the scenarios (e.g. it's probability) Why drag in set wo? So just change to Parameter s_rep(scen,*) "scenario probability" / #scen.prob 0 /; Moreover, your EMP syntax is wrong. You can either move an entire...
- 2 years ago
- Forum: Modeling
- Topic: Model running much slower on new, faster computer
- Replies: 4
- Views: 3161
Re: Model running much slower on new, faster computer
Eric,
I assume you run the same version of GAMS on both computers. What solver are you using? Perhaps, the end of the first scenario and the beginning of the next scenario (for both computers) might be sufficient to tell more.
-Michael
I assume you run the same version of GAMS on both computers. What solver are you using? Perhaps, the end of the first scenario and the beginning of the next scenario (for both computers) might be sufficient to tell more.
-Michael