An instance of the class IloCplex::MIPCallbackI represents a user-written callback in an application that uses an instance of IloCplex to solve a mixed integer program (MIP). IloCplex calls the user-written callback prior to solving each node in branch-and-cut search.

User-written callbacks of this class or any of its subclasses are not compatible with MIP dynamic search. If you are looking for support for callbacks compatible with dynamic search, consider the class IloCplex::MIPInfoCallbackI instead.

This class offers member functions for accessing an incumbent solution and its objective value from a user-written callback. It also offers methods for accessing priority orders and statistical information, such as the number of cuts. Methods are also available to query the number of generated cuts for each type of cut CPLEX generates. See the CPLEX User's Manual for more information about cuts.

The methods of this class are protected 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. For example, if there is no incumbent, the methods that query about incumbents will throw an exception.

This class also provides the common application programming interface (API) for these callback classes:

• IloCplex::NodeCallbackI
• IloCplex::IncumbentCallbackI
• IloCplex::DisjunctiveCutCallbackI
• IloCplex::FlowMIRCutCallbackI
• IloCplex::FractionalCutCallbackI
• IloCplex::ProbingCallbackI
• IloCplex::UserCutCallbackI
• IloCplex::LazyConstraintCallbackI
• IloCplex::BranchCallbackI
• IloCplex::HeuristicCallbackI
• IloCplex::SolveCallbackI

This constructor creates a callback for use in an application that uses an instance of IloCplex to solve a mixed integer program (MIP).

Returns the depth of the current node in the search tree. The root node has depth 0 (zero). The depth of other nodes is defined recursively as the depth of their parent node plus one. In other words, the depth of a node is its distance in terms of the number of branches from the root.

Returns the linear objective coefficient for var in the model currently being solved.

Returns the linear objective coefficient for var in the model currently being solved.

Puts the linear objective coefficient of each of the variables in the array vars into the corresponding element of the array vals.

Puts the linear objective coefficient of each of the variables in the array vars into the corresponding element of the array vals.

Returns the total number of parallel threads currently running.

This method returns the callback type of the invoking callback object.

Objects of this class are used to identify uniquely nodes of the branch-and-cut search tree during the solution of a MIP. When a new node is created either by IloCplex or by the user in a branch callback, IloCplex assigns a NodeId to it. From then on, the node can be referenced via this NodeId, for example, from an instance of IloCplex::NodeCallbackI.

See MIPCallbackI::NodeId.

See MIPCallbackI::NodeId.