GMP::Instance::SetCallbackBranch installs a callback
procedure to be called after a branch has been selected but before the
branch is carried out during the MIP optimization. In the callback
routine, the branch selected by the solver can be changed to a
GMP::Instance::SetCallbackBranch( GMP, ! (input) a generated mathematical program callback ! (input) an AIMMS procedure )
The procedure returns 1 on success, or 0 otherwise.
This callback is not called when the subproblem is infeasible.
In the callback procedure at most 2 branches can be specified.
The callback procedure should have exactly one argument; a scalar input element parameter into the set
CallbackBranchcallback 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.
CallbackBranchcallback procedure cannot be used to get the column on which the solver will branch.
CallbackBranchcallback procedure will only be called when solving mixed integer programs with CPLEX.