ILOG CPLEX C++ API 9.0 Reference Manual

IloCplex::NodeEvaluatorI
To implement your own node evaluator, you need to create a subclass of
IloCplex::NodeEvaluatorI and implement methods evaluate and
duplicateEvaluator. The method evaluate must be implemented to compute
and return a value for a given node. The protected methods of class
IloCplex::NodeEvaluatorI can be called to query information about the node
in order to compute this value. Each node is evaluated only once, after which the value is
attached to the node until the node is processed or pruned.
The duplicateEvaluator method is called by IloCplex when a copy of the
evaluator must be created for use in parallel branch & cut search. Thus the
implementation must simply create and return a copy of the evaluator itself—calling the
copy constructor will work in most circumstances.
Node evaluators are applied to a search defined by a goal with the method
IloCplex::Apply. The node selection strategy will be applied only to the subtree
defined by the goal passed to Apply. Using IloCplex::Apply, you can assign
different node selection strategies to different subtrees. You can also assign multiple
node selection strategies to subtrees. In this case, node selection strategies applied first
have precedence over those assigned later.
If no node evaluators are added, IloCplex uses the node selection strategy as
controlled by the NodeSel parameter.
See Also
Constructors
Methods
IloCplex, IloCplex::NodeEvaluator
public NodeEvaluatorI()
This constructor creates a node selector for use in an application with a user-defined
node selection strategy to solve a MIP.
public virtual NodeEvaluatorI * duplicateEvaluator()
This method must be implemented by the user to return a copy of the invoking object. It
is called internally to duplicate the current node evaluator for parallel branch & cut
search. This method is not called for a particular node, so the get methods cannot be
used.
public virtual IloNum evaluate()
This method must be implemented by the user to return a value for a given node. When
this method is called, the node evaluator is initialized to the node for which to compute
the value. Information about this node can be obtained by the get methods of
IloCplex::NodeEvaluatorI. Returning IloInfinity instructs IloCplex
to discard the node being evaluated.
protected IloNumVar getBranchVar()
This method returns the variable that IloCplex branched on when creating the node
being evaluated from its parent. If the node has been generated with a more complex
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