Initializing help system before first use

XPRSaddcboptnode

Purpose
Declares an optimal node callback function, called during the branch and bound search, after the LP relaxation has been solved for the current node, and after any internal cuts and heuristics have been applied, but before the Optimizer checks if the current node should be branched. This callback function will be called in addition to any callbacks already added by XPRSaddcboptnode.
Topic areas
Callback, Branch and Bound Search
Synopsis
int XPRS_CC XPRSaddcboptnode(XPRSprob prob, void (XPRS_CC *optnode)(XPRSprob cbprob, void *cbdata, int *p_infeasible), void *data, int priority);
Arguments
prob 
The current problem.
optnode 
The callback function which takes three arguments, cbprob, cbdata and p_infeasible, and has no return value.
cbprob 
The problem passed to the callback function, optnode.
cbdata 
The user-defined data passed as data when setting up the callback with XPRSaddcboptnode.
p_infeasible 
The feasibility status. If set to a nonzero value by the user, the current node will be declared infeasible.
data 
A user-defined data to be passed to the callback function, optnode.
priority 
An integer that determines the order in which multiple node-optimal callbacks will be invoked. The callback added with a higher priority will be called before a callback with a lower priority. Set to 0 if not required.
Example
The following prints the optimal objective value of the node LP relaxations: 
XPRSaddcboptnode(prob,nodeOptimal,NULL,0);
XPRSmipoptimize(prob,"");
The callback function might resemble: 
void XPRS_CC nodeOptimal(XPRSprob prob, void *data, int *p_infeasible)
{
  int node;
  double objval;

  XPRSgetintattrib(prob, XPRS_CURRENTNODE, &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 in the examples/optimizer/c folder.
See also examples addmipsol.c, knapsack.c.
Related topics
XPRSremovecboptnode, XPRSaddcbinfnode, XPRSaddcbintsol, XPRSaddcbnodecutoff, CALLBACKCOUNT_OPTNODE.

Parent Topic Console and Library Functions

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