Search found 66 matches

by PeterBe
1 year ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 26
Views: 5076

Re: MIP Start with CPLEX from a file

Thanky for your answer, I tried different values (1,2,3,4,5) for mipstart in the option file cplex.opt but all (execpt mipstart=1) yield the following errors Reading parameter(s) from "C:\Users\wi9632\bwSyncAndShare\Graduiertenkolleg\Code\GAMS\Residential Area\cplex.opt" >> mipstart=5 *** Value Erro...
by PeterBe
1 year ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 26
Views: 5076

Re: MIP Start with CPLEX from a file

Thanks for your answer cladelpino, On the other hand, it is "easy" to see if a given solution is infeasible. Why don't you figure that out so that you're sure ? Basically it is not that easy to test if a solution is feasible because I have around 10000 binary decision variables and about 10000 condi...
by PeterBe
1 year ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 26
Views: 5076

Re: MIP Start with CPLEX from a file

Thanks for your answer "cladelpino ", I tried it and in the log there is the following information: Reading parameter(s) from "C:\Users\wi9632\GAMS\cplex.opt" >> mipstart=1 ... Reading data... Starting Cplex... Space for names approximately 2.77 Mb Use option 'names no' to turn use of names off Proc...
by PeterBe
1 year ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 26
Views: 5076

Re: MIP Start with CLEP from a file

Thanks for the link. I know how parameters are exchanged between Excel and GAMS. For example if I want to load a price from a gdx file I have to write the following code: price(t) price $LOAD price" But now I do not want to load parameters, I want to transfer feasible solutions to the solver (CPLEX)...
by PeterBe
1 year ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 26
Views: 5076

MIP Start with CPLEX from a file

Hi guys, I want to use a starting solution for CPLEX. In the CPLEX manual of the GAMS webpage the following is written: "A MIP start will only be used by GAMS/CPLEX if the MipStart parameter is set to 1. The starting values must be set via the .L variable attribute in the GAMS model before the solve...
by PeterBe
1 year ago
Forum: Modeling
Topic: Ensuring realations between decision variables
Replies: 6
Views: 1700

Re: Ensuring realations between decision variables

Thanks Manassaldi for your answer, it seems to work, except for the very first two time slots. There the heating in stopped after 2 timeslots (which is not nice but not a big problem)
by PeterBe
1 year ago
Forum: Modeling
Topic: Ensuring realations between decision variables
Replies: 6
Views: 1700

Re: Ensuring realations between decision variables

Hi guys, quite a long time ago I posted the question that you can see in the first post: I have a binary variable x(t) for every minute of a day (1440). This binary variable indicates if a heating device is on or off. Now I want to ensure that the device does not switch from on to off quite frequent...
by PeterBe
1 year ago
Forum: Solvers
Topic: Computational time of model extremely increased
Replies: 9
Views: 2824

Re: Computational time of model extremely increased

Would anyone mind telling me whether my insereted code and the file are correct?
by PeterBe
1 year ago
Forum: Solvers
Topic: Computational time of model extremely increased
Replies: 9
Views: 2824

Re: Computational time of model extremely increased

Thanks for your answer Fred, I inserted the following code in GAMS: mymodel.optfile = 1; then I created a file called cplex.opt and this file looks like this: * CPLEX options file mipemphasis 2 I changed the number but nothing seemed to have an effect on the results. I always get the same results (w...
by PeterBe
1 year ago
Forum: Solvers
Topic: Computational time of model extremely increased
Replies: 9
Views: 2824

Re: Computational time of model extremely increased

Hi guys, sorry for not responding for so long. I was busy with other things. Now again the problem still remains that the computational time of my model has extremely increased altough I am not aware of any changes. I read about mipemphasis parameters: https://www.gams.com/latest/docs/S_CPLEX.html#C...