Search found 62 matches

by PeterBe
3 months ago
Forum: Syntax
Topic: Objective with if-condition
Replies: 28
Views: 1348

Re: Objective with if-condition

Hi guys, it's me again having a slightly different question as the one posted before but it has also something to do with modelling if conditions: I now have two variables x and y that with the following constraings: x + y <= 1 x + y >= 0.1 if x > 0 --> y =0 if y > 0 --> x =0 0<=x<=1 0<=y<=1 How can...
by PeterBe
3 months ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 23
Views: 1093

Re: MIP Start with CPLEX from a file

Thanks Fred for your answer, GAMS/CPLEX does not distinguish between a default 0 and an explicitly set 0. Hence, during Mipstart those zero levels are considered to be fixed as well which might be the reason that your mipstart is not accepted. But when I just use this one feasible solution I also do...
by PeterBe
3 months ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 23
Views: 1093

Re: MIP Start with CPLEX from a file

Thanks cladelpino for your answer, So, running with fixed variables finishes in "optimal solution" ? Are you initializing all variables in your problem ? Well GAMS says that it is an optimal solution (but of course this is not an optimal solution; it is just a feasible solution that I generated usin...
by PeterBe
3 months ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 23
Views: 1093

Re: MIP Start with CPLEX from a file

Thanks Fred for your answer and your help, now I got a feasible solution which I tested by x.fx(t, household) = x_Initial(t, household); y.fx(t, household) = y_Initial(t, household); So this solution is feasible and GAMS also accepts this solution. However when I want to do a MIP start with this sol...
by PeterBe
3 months ago
Forum: Syntax
Topic: Objective with if-condition
Replies: 28
Views: 1348

Re: Objective with if-condition

Thanks cladelpino for your answer,

I think (and hope) that I have understood it now :D
by PeterBe
3 months ago
Forum: Solvers
Topic: MIP Start with CPLEX from a file
Replies: 23
Views: 1093

Re: MIP Start with CPLEX from a file

Hi, it's me again having a question regarding a MIP start (sorry to bother you with my questions but I do not have that much experience with GAMS and I have no one to ask except this forum; I am really thankful for your help and appreciate it). I have a solution which I think is feasible. To check t...
by PeterBe
3 months ago
Forum: Syntax
Topic: Objective with if-condition
Replies: 28
Views: 1348

Re: Objective with if-condition

Thanks cladelpino for your answer, you wrote This is a very common misconception. The sooner you forget about it, the better your path in optimization will be. There is no difference between one type of equality constraint or the other, neither is the problem solved sequentially. The best model to r...
by PeterBe
3 months ago
Forum: Syntax
Topic: Objective with if-condition
Replies: 28
Views: 1348

Re: Objective with if-condition

@cladelpino Thanks cladelpino for your answer and help, On equation levels: Picture your equation in a way where every variable is on the left hand side of the operator (=g=,=l=, or =e=) , and on the right hand side you have (if there is any) the "constant" (determined only by parameters and constan...
by PeterBe
3 months ago
Forum: Syntax
Topic: Objective with if-condition
Replies: 28
Views: 1348

Re: Objective with if-condition

Thanks Fred for your answer, I inserted the two equations. Now a reasonable solution is found But only for one household. If I increase the number of households I always get the error message: "Row 'eq_electricalPowerTotal(144)' infeasible, all entries at implied bounds" The problematic equation loo...
by PeterBe
3 months ago
Forum: Syntax
Topic: Objective with if-condition
Replies: 28
Views: 1348

Re: Objective with if-condition

Thanks cladelpino for your answer, the values for isPositive are 0 for every timeslot in the results. There is one further aspect that I generally don't understand: What is the difference (in the result file) between the values of a variable and a corresponding equation that defines this variable? L...