Decision Optimization

Originally posted by: dbaena

Hi,
I want to use the status code CPX_TIME_LIM_FEAS or CPX_TIME_LIM_INFEAS but not in C. I am using C++ Ilog Concert. I dont find the equivalent parameter.
I need it in order to know if I have feasible solutions or not when I exit by time limit. I need it because Local Branching code use it.

Thanks a lot.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

I guess you are talking about CPXMIP_TIME_LIM_FEAS and CPXMIP_TIME_LIM_INFEAS?
I don't see these two guys in the C++ API either. But you can easily define them yourself and test like this:

if ( cplex.getCplexStatus() == IloCplex::CplexStatus(CPXMIP_TIME_LIM_FEAS) ) {
   // Aborted due to time limit, feasible solution exists.
   ...
}
else if (cplex.getCplexStatus() == IloCplex::CplexStatus(CPXMIP_TIME_LIM_INFEAS) ) {
   // Aborted due to time limit, no feasible solution eixsts.
   ...
}

Or construct a suitable switch statement.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: dbaena

Hi Daniel,

Thanks a lot, but it doesn't work. Maybe I didn't explain well. I have a MIP problem and I have done:

cplex.setParam(IloCplex::TiLim,TL);

when I do:

status=cplex.getCplexStatus() it returns the value 11.

This value is (in API C++) --> CPX_STAT_ABORT_TIME_LIM.

With this code I don't know if I have found feasible solutions or not. However, the same situation with C returns CPXMIP_TIME_LIM_FEAS or CPXMIP_TIME_LIM_INFEAS...

Thanks a lot.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

The function IloCplex::solve() (see here) returns true if a solution is available. So you just need to check what that function returns.
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#DecisionOptimization

Originally posted by: dbaena

OK. Yes, now I can do it. Thank you Daniel.
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#DecisionOptimization

Originally posted by: GuangFeng

One remark is that when you check CPLEX status by using Concert function IloCplex::getCplexStatus(), you should check the result against the values in enumeration IloCplex::CplexStatus, instead of relying on the numerical values listed in optim.cplex.solutionstatus. The reason is that Concert API has a different view of the problem from callable libraries. For example, there is no differentiation in problem types. You use IloCplex::solve() to solve all problems, but in callable libraries, you need a problem specific function.
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#DecisionOptimization

Originally posted by: dbaena

Thanks GuangFeng, but I don't understand what do you mean.
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#DecisionOptimization

Originally posted by: dbaena

Hi,

I'll solve my problem that I said, using SolutionPool of CPLEX. I explain it. Maybe it is interesting.

I do:

cplex.solve();
status = cplex.getCplexStatus();
if (status == CPX_STAT_ABORT_TIME_LIM)
{
int nsols=cplex.getSolnPoolNsolns();
if (nsols>0)
{
// I HAVE FEASIBLE SOLUTIONS
}
else
{
// INFEASIBLE SOLUTIONS
}
If you want to know the objective value of each solution you can iterate for each solution (i) and do:

cplex.getObjValue(i);
cplex.getValues(IloNumArray,IloNumVarArray,i);
I Hope it help you!
}
#CPLEXOptimizers
#DecisionOptimization