ILOG CPLEX C++ API 9.0 Reference Manual

IloCplex::BranchCallbackI
BranchCallbackI::BranchType
Inner Enumeration
Description
See Also
Constructors
Methods
An instance of the class IloCplex::BranchCallbackI represents a user-written
callback in an application that uses an instance of IloCplex to solve a mixed integer
program (MIP). The user-written callback is called prior to branching at a node in the
branch & cut tree during the optimization of a MIP. It allows you to query how the
invoking instance of IloCplex is about to create subnodes at the current node and
gives you the option to override the selection made by the invoking instance of
IloCplex. You can create zero, one, or two branches.
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The method prune removes the current node from the search tree. No subnodes
from the current node will be added to the search tree.
The method makeBranch tells an instance of IloCplex how to create a
subproblem. You may call this method zero, one, or two times in every invocation of
the branch callback. If you call it once, it creates one node; it you call it twice, it
creates two nodes (one node at each call).
If you call neither IloCplex::BranchCallBackI::prune nor
IloCplex::BranchCallBackI::makeBranch, the instance of IloCplex
proceeds with its own selection.
◆ Calling both IloCplex::BranchCallBackI::prune and
IloCplex::BranchCallBackI::makeBranch in one invocation of a
branch callback is an error and results in unspecified behavior.
The methods of this class are for use in deriving a user-written callback class and in
implementing the main method there.
If an attempt is made to access information not available to an instance of this class, an
exception is thrown.
ILOBRANCHCALLBACK0, IloCplex::BranchDirection,
IloCplex::Callback, IloCplex::CallbackI,
IloCplex::MIPCallbackI, IloCplex::ControlCallbackI
protected BranchCallbackI()
This constructor creates a branch callback, that is, a control callback for splitting a node
into two branches.
protected IloNum getBranch(IloNumVarArray vars,
IloNumArray bounds,
ILOG CPLEX C++ API 9.0 REFERENCE M ANUAL 87