ILOG CPLEX C++ API 9.0 Reference Manual

IloCplex::BranchCallbackI
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The parameter data allows you to add an object of type
IloCplex::MIPCallbackI::NodeData to the node representing the branch
created by the makeBranch call. Such data objects must be instances of a userwritten
subclass of IloCplex::MIPCallbackI::NodeData.
protected NodeId makeBranch(const IloNumVarArray vars,
const IloNumArray bounds,
const IloCplex::BranchDirectionArray dirs,
IloNum objestimate,
NodeData * data)
This method overrides the branch chosen by an instance of IloCplex. A method
named makeBranch can be called 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 it more than twice, it throws an exception.
Each call specifies a branch; in other words, it instructs the invoking IloCplex object
how to create a subnode from the current node by specifying new, tighter bounds for a
set of variables.
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The parameter vars contains the variables for which new bounds will be set in the
branch.
The parameter bounds contains the new bounds for the variables listed in vars;
that is, bounds[j] is the new bound to be set for vars[j].
◆ The parameter dirs indicates the branching direction for the variables in vars.
dir[j] == IloCplex::BranchUp
means that bounds[j] specifies a lower bound for vars[j].
dirs[j] == IloCplex::BranchDown
means that bounds[j] specifies an upper bound for vars[j].
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The parameter objestimate provides an estimate of the resulting optimal
objective value for the subnode specified by this branch. The invoking instance of
IloCplex may use this estimate to select nodes to process. Providing a wrong
estimate will not influence the correctness of he solution, but it may influence
performance. Using the objective value of the current node is usually a safe choice.
The parameter data allows you to add an object of type
IloCplex::MIPCallbackI::NodeData to the node representing the branch
created by the makeBranch call. Such data objects must be instances of a userwritten
subclass of IloCplex::MIPCallbackI::NodeData.
protected void prune()
By calling this method, you instruct the CPLEX branch & cut search not to create any
child nodes from the current node, or, in other words, to discard nodes below the current
node; it does not revisit the discarded nodes below the current node. In short, it creates
ILOG CPLEX C++ API 9.0 REFERENCE M ANUAL 91