Questions tagged [cplex]

Questions related to the commercial solver IBM ILOG CPLEX Optimization Studio.

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5
votes
2answers
108 views

Python API and CPLEX (Edited for easy instruction)

Note: See the EDIT below for one possible solution. I apologize if this is not appropriate but I don't really have anywhere else to turn. I was hoping that someone would be able to post how they ...
7
votes
2answers
337 views

CPLEX exceeds time limit issue

I am solving a MILP model using CPLEX 12.8.0, but CPLEX exceeds the time limit on some test instances. More specifically, I set the time limit for 30 minutes using the cplex.setParam(IloCplex::TiLim, ...
20
votes
4answers
4k views

What instances can be solved today by modern solvers (pure LP)?

I have found a PowerPoint presentation in which the presentor Hall claims instances could be of the size of 108 in variables and constraints to be solved today. I assume that he meant sparse problems. ...
22
votes
4answers
1k views

“Best practices” for formulating MIPs

Often there are many alternatives ways for formulating a MIP. For example: The model contains inequality constraints that must hold with equality in an optimal solution. The model contains ...
9
votes
2answers
139 views

Correct way to get a dual extreme ray for an infeasible LP in CPLEX / C++

We are coding a Benders decomposition using CPLEX/Concert (C++) and we are having some troubles to generate a feasibility cut because we are not sure how to get an extreme ray of the dual for a primal ...
9
votes
1answer
68 views

Advantages of IBM CPLEX Studio over CPLEX in MATLAB?

This question comes from the perspective of an MSc student new to both OR and programming OR problems in a MIP framework. My research has led me down this path of needing to program an optimization ...
13
votes
1answer
142 views

How to get the best bound of large LP problems in CPLEX?

When using the C callable library to solve a large LP, how can I get the best bound after calling the method CPXXlpopt? Does it depend on the algorithm used to ...
12
votes
3answers
151 views

CPLEX non-convex Quadratic Programming algorithms

CPLEX solves non-convex quadratic problems to global optimality with a global optimality option (in version 12). The relevant pages are this and this. I benchmarked many solvers, and see that CPLEX ...
7
votes
2answers
61 views

Does the API affect the time Gurobi requires to find an optimum?

When working with Gurobi, CPLEX and the like the user can choose between many different APIs, for example Python, C++, R, Java, Matlab or C. Some of these API are more efficient than others. For ...
9
votes
2answers
113 views

Using CPLEX “solution pool” to count feasible points

Some problems call for a count of the number of integer "lattice" points contained in a feasible region (rather than for locating the minimum or maximum objective function value in that region). See ...
9
votes
2answers
92 views

Advantages generic cplex callback within branch-and-cut

What are the advantages of using the generic callback compared to the old user/lazy callbacks within a branch-and-cut framework? IBM states on its website that the major benefit of the new generic ...