Search found 10 matches
- 3 years ago
- Forum: Modeling
- Topic: Cplex | Setting initial mip solution
- Replies: 2
- Views: 2093
Re: Cplex | Setting initial mip solution
Please ignore this post and consider it as closed. A preprocessing (tightening) step in gams was causing the problem.
- 3 years ago
- Forum: Syntax
- Topic: issues with gams commands
- Replies: 3
- Views: 2285
Re: issues with gams commands
Hi Fred,
thanks for your quick reply. Please find the log file attached. Or do you need something different / more?
Kind regards,
thanks for your quick reply. Please find the log file attached. Or do you need something different / more?
Kind regards,
- 3 years ago
- Forum: Modeling
- Topic: Cplex | Setting initial mip solution
- Replies: 2
- Views: 2093
Cplex | Setting initial mip solution
Hi all, i am facing a problem with setting an initial MIP solution using CPLEX. My variables are as follows: Variables x_ijk(V,V,M) y_ik(V,M) w_ik(V,M) b_ik(V,M) rt_ik(V,M) GOAL; Binary Variable x_ijk, y_ik; Positive Variable b_ik, w_ik, rt_ik; In my understanding by setting mipstart 1 option only b...
- 3 years ago
- Forum: Syntax
- Topic: issues with gams commands
- Replies: 3
- Views: 2285
issues with gams commands
Hi all, i am facing an unexpected behaviour regarding $call and $csv2gams commands which I am not able to resolve. Execution of statements like $call rmdir /S /Q 20200821_PC results in a errorstate (1, "System cannot find path"). Nevertheless, the command is executed properly (and doing th...
- 4 years ago
- Forum: Syntax
- Topic: Delete files during execution not in compile phase
- Replies: 4
- Views: 3178
Re: Delete files during execution not in compile phase
Hi all, thanks for the hints and sorry for my late response. It works perfectly! Thank you :) Currently I am facing some kind of other question using BCH facility. I am using userincbcall to identify cuts. So what happens (sample log entries): userincbcall executed: incumbent rejected (-> because pr...
- 4 years ago
- Forum: Syntax
- Topic: Delete files during execution not in compile phase
- Replies: 4
- Views: 3178
Delete files during execution not in compile phase
Hi all, I am using the usercutcall und userIncbCall functionality by the BCH facility. The logic is as follows: - userincbcall is called once incumbent solution has been determined during branch and bound (/cut) process. This might happen several times in a sequence (i.e. several incumbents are foun...
- 4 years ago
- Forum: Syntax
- Topic: BCH | Cplex | Branch and Cut
- Replies: 6
- Views: 4470
Re: BCH | Cplex | Branch and Cut
Hi Fred,
perfectly answered. Thank you for your help !
Kind regards,
Jonathan
perfectly answered. Thank you for your help !
Kind regards,
Jonathan
- 4 years ago
- Forum: Syntax
- Topic: BCH | Cplex | Branch and Cut
- Replies: 6
- Views: 4470
Re: BCH | Cplex | Branch and Cut
Hi Fred, I was able to implement it on my own. I have done two implementations and seems like both are working properly. First implementation is using BCH facility (usercutcall and userincb). Second implementation is looping over branch & bound solution process several times (and adding cuts aft...
- 4 years ago
- Forum: Syntax
- Topic: BCH | Cplex | Branch and Cut
- Replies: 6
- Views: 4470
Re: BCH | Cplex | Branch and Cut
Hi Fred, I have been checking the bchtsp.gms before and took some code samples from it. My rework of the code fragments led to the unresolvable issue. It looks much better now. Thank you! In the meantime I have been working on the code and made some more improvements (and fixes). It is running and g...
- 4 years ago
- Forum: Syntax
- Topic: BCH | Cplex | Branch and Cut
- Replies: 6
- Views: 4470
BCH | Cplex | Branch and Cut
Hi all, currently I am trying to implement an simple branch and cut algorithm using the GAMS Branch & Cut Facility and CPLEX. In a simple implementation a relaxed problem formulation is strengthened in branching process by providing some additional cuts (Problem VRP). A relaxed MIP problem formu...