[FIXED] How to enable linear relaxation outputs

Issue

I have a rather complex MILP, but the main problem is the number of continuous variables, not the number of binaries. I just "hard-coded" the linear relaxation to understand its output, and it takes approx. 10-15 minutes to solve (which is not extremely surprising). If I run the MILP with outputs, I don't see anything happening for the first 10 minutes, because it takes those 10 minutes to construct a first integer-feasible solution. So it would help to be able to enable the same outputs I am seeing when solving the linear relaxation "manually" (so something like Iteration: 1 Dual objective = 52322816.412592) within the B&B output.

Is this possible? I googled at bit, but I only found solutions for steering the solution algorithm, or for deriving linear relaxations using callbacks, while I am interested in a "simple" output of the intermediate steps.

Solution

It sounds like you are asking for extra detailed logging during the linear relaxation part of the solve during the B&B. Have a look at the CPLEX parameter settings like IloCplex.Param.MIP.Display (try setting this to 5) and also IloCplex.Param.Simplex.Display (try setting to 1 or 2).

Answered By - TimChippingtonDerrick

Answer Checked By - Cary Denson (PHPFixing Admin)