Search found 31 matches

by moosavi_69
3 years ago
Forum: Tools
Topic: CPLEX presolve for dual bound value
Replies: 1
Views: 2601

CPLEX presolve for dual bound value

Hello, I have an MIP model and intend to solve it with the CPLEX solver. It happens that the CPLEX cannot find an initial solution for a few large-scale instances in a limited time. So, I would like to know whether there is any way that I can use the CPLEX presolve to report a dual bound value for t...
by moosavi_69
3 years ago
Forum: Syntax
Topic: Use index for another index
Replies: 3
Views: 2874

Re: Use index for another index

Thank you. I want to remove a few elements from the two-dimensional set that I have created. However, it does not work. Do you have any suggestions? Sets c /1*10/ t /1*10/ tc(c,t) /#c.#t/; Parameters p(c) /1 3, 2 4, 3 5, 4 2, 5 3, 6 4, 7 5, 8 6, 9 5, 10 5/; loop((c,t), if(ord(t)-p(c)+1>card(t), tc(c...
by moosavi_69
3 years ago
Forum: Syntax
Topic: Use index for another index
Replies: 3
Views: 2874

Use index for another index

Hello, Let assume I have an index c and j as follows: c /1*10/ j /1*3/ Now, I would like to define subsets of c as below: c_j c_j, for example, can be as follows: c_1 /1*5/ c_2 /5*10/ c_3 /4*6/ So, I can write a constraint like below: Con(j) .. sum((c_j,r,d), x(c_j,r,d)) =l= y(j); How can I define c...
by moosavi_69
3 years ago
Forum: Syntax
Topic: Variable Reslim time
Replies: 10
Views: 6664

Re: Variable Reslim time

Exactly! My GAMS was not up-to-date. Thanks!
by moosavi_69
3 years ago
Forum: Syntax
Topic: Variable Reslim time
Replies: 10
Views: 6664

Re: Variable Reslim time

I implemented the below code, but it does not properly terminate the code. I have set the time limit equal to 10 seconds. Although the CPLEX solver finds a feasible solution with a gap of about 4%, it does not terminate after 10 seconds! Model MOBJ /Obj1, Obj2, Con3, Con4, Con5, Con6, Con8, Con9, Co...
by moosavi_69
3 years ago
Forum: Syntax
Topic: Variable Reslim time
Replies: 10
Views: 6664

Re: Variable Reslim time

This is fantastic. Thank you!!!
by moosavi_69
3 years ago
Forum: Syntax
Topic: Variable Reslim time
Replies: 10
Views: 6664

Re: Variable Reslim time

Thanks for your attention again. The thing is that I like to find the optimal solution given a limited computational cost. I do not want to terminate the solver as long as it has not used its initial allocated CPU time (300 seconds in the previous example) and not found the optimal solution. If it f...
by moosavi_69
3 years ago
Forum: Syntax
Topic: Variable Reslim time
Replies: 10
Views: 6664

Re: Variable Reslim time

Thanks for your reply. It worked for me. Now, I have another question. Your attention is very much appreciated. Let us say that I want to solve three models as follows: LTC.reslim=300; Solve LTC using MIP min f1; Solve LTC using MIP min f2; Solve LTC using MIP min f3; I give an initial max CPU time ...
by moosavi_69
3 years ago
Forum: Syntax
Topic: Variable Reslim time
Replies: 10
Views: 6664

Variable Reslim time

Hello, Let us assume that I would like to solve a specific model (with different inputs) ten times. I have a maximum of 3,000 seconds time limit for all runs. At first, I need to assume that the time limit for each run of the model is 300 seconds. However, for example, if the first run of the model ...
by moosavi_69
3 years ago
Forum: Syntax
Topic: routing problem
Replies: 1
Views: 1501

Re: routing problem

Dear Amirhossein,

It is happening because your model cannot control such situations. If you have already designed constraints for these infeasibilities, you should check why they are not working properly. If you have not included any yet, you should design one.

Best, Amirhossein