Search found 6 matches

by mosalari
6 months ago
Forum: Modeling
Topic: How to adjust a Matrix in the process of solving a model.
Replies: 3
Views: 775

Re: How to adjust a Matrix in the process of solving a model.

Thank you for your reply. What if the following information is not given:
n out of m "x" should be equal to one and other x's are zero.

I mean what if we don't know how many x(m) will be equal to 1. Can we still solve the problem?
by mosalari
9 months ago
Forum: Solvers
Topic: Option file for CPLEX solver
Replies: 4
Views: 890

Re: Option file for CPLEX solver

Thank you. I tried it but it doesn't work. I still have an absolute gap. here is the report from GAMS: MIP status (107): time limit exceeded So, it seems the problem is the time limit. How can I have an unbounded time limit? absolute gap is the upper bound for the distance between best integer and o...
by mosalari
9 months ago
Forum: Solvers
Topic: Option file for CPLEX solver
Replies: 4
Views: 890

Re: Option file for CPLEX solver

GAMS read the options file. here is the report from GAMS: MIP status (107): time limit exceeded So, it seems the problem is the time limit. How can I have an unbounded time limit? There are two possibilities: a) GAMS/CPLEX did not process the option file, or b) Cplex terminated on time/iteration/......
by mosalari
9 months ago
Forum: Solvers
Topic: Option file for CPLEX solver
Replies: 4
Views: 890

Option file for CPLEX solver

Hi all, I use CPLEX solver to solve the MIP problems, but this solver tends to give the results as below for instance: MIP Solution: 207.200000 (9469739 iterations, 151607 nodes) Final Solve: 207.200000 (0 iterations) Best possible: 151.594951 Absolute gap: 55.605049 Relative gap: 0.268364 I wanna h...
by mosalari
1 year ago
Forum: Modeling
Topic: how to invert a variable
Replies: 1
Views: 476

how to invert a variable

Hi all,
we know that there is a function to calculate the inverse of a matrix in GAMS, but how can we calculate the inverse of a variable ?
For instance, in the middle of our optimization process, we have the values of the variable B
B has two indices B(n*n)
And we want to calculate the inverse of B.
by mosalari
1 year ago
Forum: Modeling
Topic: How to adjust a Matrix in the process of solving a model.
Replies: 3
Views: 775

How to adjust a Matrix in the process of solving a model.

Hi all, I have a matrix, let's call it A, as an input which has the following characteristics: Total number of rows=n Total number of columns=m n<m we also have a binary variable, x, and its index is m. it means we have: x(1), x(2),....,x(m). during the optimization process n out of m "x" should be ...