Search found 23 matches

by abb.omidi
1 month ago
Forum: Modeling
Topic: Special constraint formulation
Replies: 0
Views: 371

Special constraint formulation

Hello community team, I have tried to write a scheduling problem which has been described by Sousa and Wolsey in machine scheduling. I'm going to use two different approaches to write my code. First, using the special syntax into the constraint and second, create dynamic sets. The following code des...
by abb.omidi
1 month ago
Forum: Modeling
Topic: How to execute a warm start using GAMS/Cplex
Replies: 0
Views: 246

How to execute a warm start using GAMS/Cplex

Dear community team, I have tried to solve a scheduling model. I would like to use a warm start to solve my problem because The model takes much time to solve optimally even for a small set of given data. The model statistic and what I'm looking for are as follows. The original model, a small instan...
by abb.omidi
2 months ago
Forum: Modeling
Topic: GAMS/convert solver
Replies: 2
Views: 558

Re: GAMS/convert solver

Dear Fred,

Thanks so much for your reply. Would you say, is there any way to get a (.MPS) like format from GAMS, please?

Regards
Abbas
by abb.omidi
2 months ago
Forum: Modeling
Topic: GAMS/convert solver
Replies: 2
Views: 558

GAMS/convert solver

Dear community, I have tried to use convert facility to write a (.MPS) file from an NLP solver. The code is as follows: model Mark_cut / all /; *** Modifications * choose convert as solver option nlp = convert; ** write convert option file $echo fixedmps Mark_cut.mps > convert.opt ** instruct conver...
by abb.omidi
3 months ago
Forum: Tools
Topic: Get a MPS file using NEOS/GAMS web interface
Replies: 1
Views: 532

Get a MPS file using NEOS/GAMS web interface

Dear community team, I'm trying to use Neos/GAMS to solve an optimization problem. I will need to get a MPS file from the model. With using GAMS IDE it is easy to use an option file to get it but, it needs a licence file for large models. My question is, is there any way to get an MPS file using the...
by abb.omidi
3 months ago
Forum: Modeling
Topic: Connecting GAMS 28.1.0 to neos server
Replies: 3
Views: 304

Re: Connecting GAMS 28.1.0 to neos server

Dear Fred, Thanks for your comment. I was trying to solve the attached example using GAMS/Kestrel via GAMS studio 28.1.0. When I solve the model log file is as follows: --- Job GAMS..Kestrel.gms Start 08/20/19 10:29:58 28.1.0 r5b48834 WEX-WEI x86 64bit/MS Windows --- GAMS Parameters defined Input C:...
by abb.omidi
3 months ago
Forum: Modeling
Topic: Connecting GAMS 28.1.0 to neos server
Replies: 3
Views: 304

Connecting GAMS 28.1.0 to neos server

Dear support team, I'm trying to run the GAMS model using neos-server. I wrote the following code in the GAMS studio: Option mip=kestrel; sequence.optfile=1; $onecho > kestrel.opt kestrel_solver cplex neos_server www.neos-server.org:3333 $offecho But it doesn't work. I was wondering if, how can I co...
by abb.omidi
5 months ago
Forum: Modeling
Topic: Modeling the chance constraints
Replies: 0
Views: 503

Modeling the chance constraints

Hello support team, I have worked on the MIP model that contains the chance constraints. The constraint is: probability_cons.. prob[sum(j, a(j)*x(j)) =l= b] =g= beta; Where a(j) and b are given parameters and beta is the probability. I was wondering if, you say that, is there any efficient way to wr...
by abb.omidi
6 months ago
Forum: API
Topic: Read a MPS/LP file in Java
Replies: 1
Views: 565

Read a MPS/LP file in Java

Hello support team,

Would you please, say that is there any way (or any example) to read an "MPS/LP" file in the GAMS Java API and get output in the specific format? If so, could you advise me, please?

Regards
Omidi. A
by abb.omidi
7 months ago
Forum: Modeling
Topic: Using SOS type_1 constraint
Replies: 2
Views: 341

Re: Using SOS type_1 constraint

Dear Fred, Thanks for your useful comment. As per your advice, I try to use a medium scale problem using both binary and SOS1 variables. The results and solving time are the same. I think using of SOS1 does not improve solving time (in my problem). Unfortunately, I can not understand why GUROBI (Jav...