Originally posted by: amindehghanian

Hi,

When CPXlpopt is done successfully, I use CPXgetx, but I got the strange value of 1217 as my status???

What does it mean?

Thanks,

Status 1217 is CPXERR_NO_SOLN: no solution available.

What do you mean by "CPXlpopt() is done successfully"? If that function returns 0 this does not mean that a solution is available. Your problem may be infeasible and CPXlpopt() may have successfully proven that. You need to check the solution status using function CPXgetstat() to make sure you have a feasible solution (a list of solution statuses can be found here).

Originally posted by: amindehghanian

Daniel,

Thanks for your quick!

If I use CPXgetstat, it returns 0 to me!  Any clue?

Thanks again,

Originally posted by: amindehghanian

It might be worth to mention that I create this LP at the beginning of my code and I use it as a cut generator in a branch-and-cut for solving my MILP master problem. Furthermore, I add more constraints to this LP by using CPXaddrows in my cutcallback function.

The issue is that if I solve my lp immediately after creating it, I still observe the same thing for CPXgetx.

Thanks,

Does the CPLEX log output give any clue as to what may be going on? Can you please attach the log output here? Can you also export the model as a SAV file and attach it here?

Originally posted by: amindehghanian

The issue was that when I was using CPXnewcols, my ctype entry was not empty while all the variables were put to be continuous. Since ctype was not NULL, CPLEX considers this problem as an MILP rather than LP.

Thanks for your answers!

I'm not a C user, but I think that a call to CPXsolninfo might reveal whether CPLEX determined the problem to be infeasible, or unbounded during presolve (which I think can result in no feasible solution being determined).

Paul