Originally posted by: mrmag

Hello!

I want to get intermediate information about the best integer solution found (if an optimal is not found because of the time limit) during the search of CPLEX. For that purpose I created the following callback function:

ILOMIPINFOCALLBACK2(loggingCallback,
IloCplex, cplex,
IloNum, timeStart
)
{
if ( hasIncumbent() ) {
cout << getIncumbentObjValue() << endl;
cout << getNnodes() << endl;
cout << cplex.getCplexTime() – timeStart << endl;
cout << getNcuts(IloCplex::CutClique)+ getNcuts(IloCplex::CutCover) << endl;
}
}
// ...
cplex.use(loggingCallback(env, cplex, cplex.getCplexTime()));

Everything works find except the function getNcuts(). The program terminates with the following exception:

>> Concert exception caught: CPLEX Error 1003: Bad argument to Callable Library function.

Is there any method to get the number of cuts which were applied during the search up to the moment the current integer solution was found?
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

What version of CPLEX do you use? I tried 12.5 and 12.4.0.1 here and with both of them your code did work without trouble.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: mrmag

Hello Daniel,

I use CPLEX 12.4 and it definitively shows that error message. I will try to update my CPLEX.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

Very weird. Even with 12.4.0.0 I cannot reproduce your problem.
Can you please double check that you did post all the relevant code?
I have attached the program that I used for testing. Maybe you can check whether it works for you?
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: mrmag

Hello Daniel,

I updated the CPLEX to version 12.5 and the error disappeared. That’s fine now. Thank you.

The idea of the code was the following. Every time CPLEX finds a better feasible integer solution I save the time, number of nodes and cuts which were generated in order to get this solution. For that purpose I designed the following code (also attached to the message):

ILOMIPINFOCALLBACK7
(loggingCallback,
IloCplex, cplex,
IloNum, timeStart,
IloNum &, outObjValue,
IloInt &, outNnodes,
IloNum &, outTime,
IloInt &, outNcuts,
IloInt &, outUserCuts
)
{
try
{
if ( hasIncumbent() && getIncumbentObjValue() < outObjValue ) {
outObjValue=getIncumbentObjValue();
outNnodes=getNnodes();
outTime=cplex.getCplexTime() - timeStart;
outNcuts=cplex.getNcuts(IloCplex::CutClique);
outUserCuts=getNcuts(IloCplex::CutUser);
}
}
catch (IloException& e) {
std::cerr << "Concert exception caught: " << e << std::endl;
}
catch (std::string exs) {
std::cerr << exs << std::endl;
}
}

which runs with the following exception:

>> Concert exception caught: CPLEX Error 1217: No solution exists.

But there are solutions. Is there any proper way to solve that problem?
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

That looks like a bug. Unfortunately, I cannot reproduce that here (using CPLEX 12.5.0.0 and your code). Can you tell which of the functions in the callback throws the exception?
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: mrmag

Hello Daniel,

the function which throws the exception is getNcuts(). I found out that the user must not call cplex.getNcuts(), but the one in the ILOMIPINFOCALL invironment. It still throws the exception with parameters like CutUser and so on. But it does not throw the exception with the common cuts like CutClique. So, it is okay now and the question is answered. Thank you for help.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

You are right. Querying the number of user cuts is not supported from the MIP info callback. I will investigate and either file a bug report or a user wish for that.
#CPLEXOptimizers
#DecisionOptimization