Search found 158 matches

by Fred
1 week ago
Forum: Modeling
Topic: GAMS/convert solver
Replies: 2
Views: 73

Re: GAMS/convert solver

Hi, MPS is a file format for linear problems: https://en.wikipedia.org/wiki/MPS_(format) If you look into the resulting mps file, you should see hints like * Cannot handle NLP [...] * Cannot handle nonlinear equations, nonlinear part ignored. * Cannot handle nonlinear equations, nonlinear part ignor...
by Fred
1 week ago
Forum: Syntax
Topic: Dynamic set allocation with binary variable
Replies: 10
Views: 236

Re: Dynamic set allocation with binary variable

Hi, you are absolutely right. I edited my post accordingly.

Fred
by Fred
1 week ago
Forum: Syntax
Topic: Dynamic set allocation with binary variable
Replies: 10
Views: 236

Re: Dynamic set allocation with binary variable

Hi, So you want a constraint that calculates the sum of all distances w(p1,p2) between pixels p1 and p2 on which a house h is built? I think a straightforward (quadratic) formulation could look as follows: equation houseDistNL; positive variable distNL; alias(h,h1,h2), (p,p1,p2); houseDistNL.. distN...
by Fred
1 week ago
Forum: Syntax
Topic: Dynamic set allocation with binary variable
Replies: 10
Views: 236

Re: Dynamic set allocation with binary variable

Hi, The dynamic set won't help if you need that during the solution process. I guess there are model formulations that do what you want but it is a bit tedious to guess how this could fit into an unknown model. If you share your model and explain where you are struggling to find the right formulatio...
by Fred
1 week ago
Forum: Syntax
Topic: Dynamic set allocation with binary variable
Replies: 10
Views: 236

Re: Dynamic set allocation with binary variable

Hi, Your syntax is almost corrrect. It only misses the level attribute of the variable (https://www.gams.com/latest/docs/UG_Variables.html#UG_Variables_VariableAttributes) and it seem that h is a set elemnt which means it should be quoted. Also, I suggest not to test for equality (due to tolerances ...
by Fred
1 week ago
Forum: Modeling
Topic: Problem with creating a constraint for a minimum amount of consecutive days
Replies: 1
Views: 88

Re: Problem with creating a constraint for a minimum amount of consecutive days

Hi, I think the following example should do the trick. binary variable y(i,l) 'worker i works on day l'; variable start(i,l) 'value of 1 indicates that worker i starts to work on day l'; equation defStart(i,l) minconsec(i,l); defStart(i,l).. start(i,l) =e= y(i,l) - y(i,l-1); minconsec(i,l)$(ord(l)>1...
by Fred
3 weeks ago
Forum: Syntax
Topic: Error 66 even when all symbols are defined and assigned... help!
Replies: 2
Views: 104

Re: Error 66 even when all symbols are defined and assigned... help!

Hi, If you look into the listing file, the first error you get is **** $66,256,299 UNEXPECTED END OF FILE (1) **** 3 ERROR(S) 0 WARNING(S) After adding a semicolon after the solve statement yo get 79414 solve MEPI using mip minimizing of; **** $66,256 **** LINE 251 INPUT C:\Users\user\Documents\supp...
by Fred
1 month ago
Forum: Modeling
Topic: cplex error 1217 :no solution exists.
Replies: 1
Views: 96

Re: cplex error 1217 :no solution exists.

Hi, Your model is (integer) infeasible. So there is no feasible point to all the constraints and integrality requirements you have specified. You either made a mistake implementing some constraint, or the combination of model and data really allows for no feasible solution. This state of the optimiz...
by Fred
1 month ago
Forum: Modeling
Topic: Connecting GAMS 28.1.0 to neos server
Replies: 3
Views: 168

Re: Connecting GAMS 28.1.0 to neos server

Hi,

To help you it would be good to know how exactly your code fails (share log, lst and files to reproduce). If I adopt your code snippet to model from the model library, everything works as expected.

Best,
Fred
by Fred
1 month ago
Forum: Solvers
Topic: Solver stop conditions
Replies: 1
Views: 351

Re: Solver stop conditions

Hi,

The Baron options DeltaTerm, DeltaT, DeltaR, DeltaA seem to be what you are looking for: https://www.gams.com/latest/docs/S_BARO ... ermination

I hope this helps!

Fred