Search found 106 matches

by bussieck
4 hours ago
Forum: Announcements
Topic: GAMS Distribution 25.1.1 Announcement
Replies: 0
Views: 3

GAMS Distribution 25.1.1 Announcement

Hi GAMS Users, We started distributing GAMS Release 25.1.1 on May 19, 2018. This release contains the first preview version of GAMS Studio - a completely new integrated development environment for GAMS. GAMS Studio is still in a very early stage of development, but we believe it is already mature en...
by bussieck
4 days ago
Forum: Syntax
Topic: how a parameter used as set in equation
Replies: 2
Views: 29

Re: how a parameter used as set in equation

I suggest investing a little more time learning before you seek help here, see the rules of the forum ( https://forum.gamsworld.org/app.php/rules ). There is good tutorial material out there. As a starter: https://www.gams.com/latest/docs/UG_MAIN.html#UG_Tutorial_Examples and https://www.youtube.com...
by bussieck
5 days ago
Forum: Modeling
Topic: Error in MIQCP sample model
Replies: 3
Views: 52

Re: Error in MIQCP sample model

Sean,

**2 is real-power (rpower, see https://www.gams.com/latest/docs/UG_Par ... s_dmrpower) and requires NLP model type. For quadratic models you need to use power or sqr.

-Michael
by bussieck
5 days ago
Forum: Modeling
Topic: Error: integer infeasible No solution exists
Replies: 1
Views: 22

Re: Error: integer infeasible No solution exists

That's not an error. Optimal, infeasible and unbounded are the three acceptable states of a mathematical program. You might not want to have an infeasible model but that's your issue. There are lots of good write-ups about how to deal with infeasible model, e.g. Bruce McCarl's excerpt which you find...
by bussieck
1 week ago
Forum: Solvers
Topic: normal compilation but Constraints not satisfied
Replies: 1
Views: 24

Re: normal compilation but Constraints not satisfied

"Normal completion" is the solver status code. You need to look at the model status. Infeasible or unbounded are also very fine model status codes in optimization. Perhaps BARON found your model to be infeasible.

-Michael
by bussieck
1 week ago
Forum: Modeling
Topic: MIP - CPLEX solver does not give optimal solution in a facility location problem
Replies: 4
Views: 64

Re: MIP - CPLEX solver does not give optimal solution in a facility location problem

I said optCR (not scaleOpt)! If I set optCR to 0 both models return the same objective: max7: Proven optimal solution. MIP Solution: 25415486.875000 (55 iterations, 0 nodes) Final Solve: 25415486.875000 (20 iterations) Best possible: 25415486.875000 Absolute gap: 0.000000 Relative gap: 0.000000 all1...
by bussieck
1 week ago
Forum: Solvers
Topic: Threads in solving a MIP with Cplex
Replies: 1
Views: 15

Re: Threads in solving a MIP with Cplex

Somewhere in the Cplex log you will find "Parallel mode: deterministic, using up to 8 threads." Also at the end you see a summary which you don't see if you run sequential: Root node processing (before b&c): Real time = 0.25 sec. (48.12 ticks) Parallel b&c, 8 threads: Real time = 0.00 sec. (0.20 tic...
by bussieck
2 weeks ago
Forum: Modeling
Topic: Infeasible Solution
Replies: 4
Views: 117

Re: Infeasible Solution

Andreas,

I would go to your advisor and get help. That's what they are paid for!

-Michael
by bussieck
2 weeks ago
Forum: Solvers
Topic: Why do DICOPT and BARON come to contradictory conclusions?
Replies: 9
Views: 219

Re: Why can the solvers only give local optimals of my model?

I agree that this does not look right. There might be a couple of explanations (including bugs in DICOPT and/or BARON), but without being able to reproduce things, there is little we can do. So why don't you upload the model that solves to local optimality with DICOPT but where BARON reports infeasi...