ILOG CPLEX 11.0 User's Manual

Query or Diagnostic CallbacksQuery or diagnostic callbacks allow you to monitor an ongoing optimization, and optionallyto abort it (that is, to terminate it). Query callbacks access more detailed information aboutthe current optimization than do informational callbacks. As a side effect, query ordiagnostic callbacks may slow progress. Furthermore, query or diagnostic callbacks makeassumptions about the traversal of a conventional branch & cut tree; those assumptionsabout a mixed integer program (MIP) may be incorrect during during dynamic search orduring deterministic search in parallel optimization. For more detail about this point, seeQuery Callbacks and Dynamic Search on page 451 and Query Callbacks and DeterministicParallel Search on page 451.Where Query Callbacks Are CalledQuery or diagnostic callbacks are distinguished by the place where they are called during anoptimization. There are nine such places where ILOG CPLEX calls a query or diagnosticcallback:◆◆◆◆The presolve query callback is called regularly during presolve.●●●●IloCplex::PresolveCallbackI in the C++ APIIloCplex.PresolveCallback in the Java APICplex.PresolveCallback in the .NET APICPXsetlpcallbackfunc in the Callable Library (C API)The crossover query callback is called regularly during crossover from a barrier solutionto a simplex basis.●●●●IloCplex::CrossoverCallbackI in the C++ APIIloCplex.CrossoverCallback in the Java APICplex.CrossoverCallback in the .NET APICPXsetlpcallbackfunc in the Callable Library (C API)The network query callback is called regularly during the network simplex algorithm.●●●●IloCplex::NetworkCallbackI in the C++ APIIloCplex.NetworkCallback in the Java APICplex.NetworkCallback in the .NET APICPXsetnetcallbackfunc in the Callable Library (C API)The barrier query callback is called at each iteration during the barrier algorithm.ILOG CPLEX 11.0 — USER’ S MANUAL 449