Originally posted by: CDYD_Victor_Miller

I have a C++ program, using concert technology, which reads in the description of one of  a family of problems, and then, depending on various flags, generates different problems for cplex top optimize.  I have one option which generates a quadratic objective function where all the variables are boolean (i.e. 0/1) without any other constraints.  This has been working without problem, except for one particular input that I have, which causes the error "IloAlgorithm cannot extract extractable".  What's puzzling, is that there doesn't appear to be anything different about this particular problem than a whole bunch of others.  Are there any suggestions for debugging this?  My version of cplex is 12.5.0.0 running on x86_64 Linux redhat.

Try printing the IloModel (or exporting it to an LP file) before calling solve. Is it possible that in this particular instance you either refer to a variable that was never created or have a term whose coefficient was never initialized?

Try catching the CannotExtractException (a subclass of IloException). This exception reports the extractables that CPLEX failed to extract:

try {
   ...
} catch (IloAlgorithm::CannotExtractException &e) {
   IloExtractArray &failed = e.getExtractables();
   std::cerr << "Failed to extract:" << std::endl;
   for (IloInt i = 0; i < failed.getSize(); ++i)
      std::cerr << "\t" << failed[i] << std::endl;
} catch (IloException &e ) {
   ...
}