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XPRSsetcboptnode

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Purpose

Declares an optimal node callback function, called after an optimal solution for the current node has been found during the Branch and Bound search.

Synopsis

int XPRS_CC XPRSsetcboptnode(XPRSprob prob, void (XPRS_CC *fuon)(XPRSprob my_prob, void *my_object, int *feas), void *object);

Arguments

prob	The current problem.
fuon	The callback function which takes three arguments, my_prob, my_object and feas, and has no return value.
my_prob	The problem passed to the callback function, fuon.
my_object	The user-defined object passed as object when setting up the callback with XPRSsetcboptnode.
feas	The feasibility status. If set to a nonzero value by the user, the current node will be declared infeasible.
object	A user-defined object to be passed to the callback function, fuon.

Example

The following prints an optimal solution once found:

XPRSsetcboptnode(prob,nodeOptimal,NULL);
XPRSmaxim(prob,"g");

The callback function might resemble:

void XPRS_CC nodeOptimal(XPRSprob prob, void *obj, int *feas)
{
  int node;
  double objval;

  XPRSgetintattrib(prob, XPRS_NODES, &node);
  printf("NodeOptimal: node number %d\n", node);
  XPRSgetdblattrib(prob, XPRS_LPOBJVAL, &objval);
  printf("\tObjective function value = %f\n", objval);
}

See the example depthfirst.c on the Xpress‑MP CD-ROM.

Further information

The cost of optimizing the node will be avoided if the node is declared to be infeasible from this callback function.

Related topics

XPRSsetcbchgnode, XPRSsetcbinfnode, XPRSsetcbintsol, XPRSsetcbnodecutoff, XPRSsetcbchgbranch, XPRSsetcbprenode.

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