Procedure GMP::Instance::SetCallbackHeuristic(GMP, callback)

# GMP::Instance::SetCallbackHeuristic¶

The procedure GMP::Instance::SetCallbackHeuristic installs a callback procedure that is called during the solution process of a MIP model every time the subproblem has been solved to optimality.

GMP::Instance::SetCallbackHeuristic(
GMP,            ! (input) a generated mathematical program
callback        ! (input) an AIMMS procedure
)


## Arguments¶

GMP

An element in AllGeneratedMathematicalPrograms.

callback

A reference to a procedure in the set AllIdentifiers.

## Return Value¶

The procedure returns 1 on success, or 0 otherwise.

Note

• This callback is not called when the subproblem is infeasible or cut off.

• The callback should supply the solver with a heuristically-derived integer solution.

• The callback procedure should have exactly one argument; a scalar input element parameter into the set AllSolverSessions.

• The CallbackHeuristic callback procedure should have a return value of

• 0, if you want the solution process to stop, or

• 1, if you want the solution process to continue.

• To remove the callback the empty element should be used as the callback argument.

• A CallbackHeuristic callback procedure will only be called when solving mixed integer programs with CPLEX, GUROBI or ODH-CPLEX.