[Coin-discuss] Construct a MIP problem

[Ted Ralphs]

John J Forrest wrote:
> 
> Looking OsiCpx it looks as if it sets coltype_ in OsiCpx correctly but 
> if it is not a MIP in Cplex does not tell Cplex. Using writeMpsNative 
> should work.

Yes, the problem is that CPLEX will not store integrality information 
unless it thinks the problem is a MIP. By default, problems loaded into 
Osi are considered LPs. It is only when branchAndBound() is called that 
the problem type is set to MIP. This is an issue specific to CPLEX---I 
believe all of the other solvers will store integrality information even 
when the problem is being solved as an LP.

Ted
-- 
Dr. Ted Ralphs
Assistant Professor
Industrial and Systems Engineering
Lehigh University
(610)758-4784
tkralphs at lehigh.edu
www.lehigh.edu/~tkr2