Search found 108 matches

by cladelpino
2 years ago
Forum: Solvers
Topic: CPLEX stuck "Removing shift" on MILP
Replies: 3
Views: 1206

Re: CPLEX stuck "Removing shift" on MILP

Steve: Thanks for your reply, we will see if we can manage the time to get this to a reproducible case but I'm guessing this will be difficult since its a very hard problem and solve takes very long so it will be hard to pinpoint the problem. I'm sorry for my conceptual mixup. I had misunderstood th...
by cladelpino
2 years ago
Forum: Solvers
Topic: Problems with the initial point
Replies: 4
Views: 1582

Re: Problems with the initial point

This is the expected behaviour, as far as I understand. From http://www.gams.com/latest/docs/userguides/userguide/_u_g__tutorial.html : "The default initial level is zero unless zero is not within the bounded range, in which case it is the bound closest to zero" This is of course not convenient for ...
by cladelpino
2 years ago
Forum: Solvers
Topic: CPLEX stuck "Removing shift" on MILP
Replies: 3
Views: 1206

CPLEX stuck "Removing shift" on MILP

Hi all. We are trying to solve a MILP, but a particular instance gets consistently stuck at a point in the solve. Looking at the detailed log we can see that the process is stuck while performing the "Removing shift" step after achieving dual infeasibility for the node. It just keeps writing this to...
by cladelpino
2 years ago
Forum: Solvers
Topic: Problem with the Model status with Antigone solver
Replies: 9
Views: 2254

Re: Problem with the Model status with Antigone solver

As I understand, there is no other possible model status for GAMS after a succesful solve for an NLP that a local optimum. The GAMS manual explicitly mentions this in http://www.gams.com/latest/docs/userguides/mccarl/modelstat_tmodstat.htm I'm not a global optimization expert, so the real question f...
by cladelpino
2 years ago
Forum: Solvers
Topic: BONMIN branch and bound
Replies: 2
Views: 1283

Re: BONMIN branch and bound

Thanks Michael, indeed most solvers have quite obscure logs. I would have to do the research but it seemed worth giving the new forums a shot for anyone familiarized with the math behind BONMIN. Nice to see gamsworld back, btw !

Regards!
Claudio
by cladelpino
2 years ago
Forum: Tools
Topic: Saving solution with partial solve, and restarting solve
Replies: 2
Views: 1339

Re: Saving solution with partial solve, and restarting solve

Setting:

option reslim=600

Will make the solver stop after 10 minutes. You can also consider iterlim for a stopping based on the number of iterations.

http://www.gams.com/latest/docs/usergui ... eslim2.htm
http://www.gams.com/latest/docs/usergui ... terlim.htm


Regards!
Claudio
by cladelpino
2 years ago
Forum: Solvers
Topic: BONMIN branch and bound
Replies: 2
Views: 1283

BONMIN branch and bound

Hi all, I am now trying BONMIN on a MINLP, chose to began with B&B just for the fun of "watching" the tree grow :) . I don't understand the following process I'm seeing in the solver log: As you can see there seems to be reports of two different kinds NLPs being run, which I marked in italics and bo...