Initializing help system before first use

XPRSaddcbintsol

Purpose
Declares a user integer solution callback function, called every time an integer solution is found by heuristics or during the Branch and Bound search. This callback function will be called in addition to any callbacks already added by XPRSaddcbintsol.
Topic areas
Callback, Solution
Synopsis
int XPRS_CC XPRSaddcbintsol(XPRSprob prob, void (XPRS_CC *intsol)(XPRSprob cbprob, void *cbdata), void *data, int priority);
Arguments
prob 
The current problem.
intsol 
The callback function which takes two arguments, cbprob and cbdata, and has no return value. This function is called if the current node is found to have an integer feasible solution, i.e. every time an integer feasible solution is found.
cbprob 
The problem passed to the callback function, intsol.
cbdata 
The user-defined data passed as data when setting up the callback with XPRSaddcbintsol.
data 
A user-defined data to be passed to the callback function, intsol.
priority 
An integer that determines the order in which multiple integer solution 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 example prints integer solutions as they are discovered in the tree search: 
XPRSaddcbintsol(prob,printsol,NULL,0);
XPRSmipoptimize(prob,"");
The callback function might resemble: 
void XPRS_CC printsol(XPRSprob cbprob, void *data)
{
  int i, cols;
  double objval, *x;

  XPRSgetintattrib(cbprob, XPRS_INPUTCOLS, &cols);
  XPRSgetdblattrib(cbprob, XPRS_LPOBJVAL, &objval);
  x = malloc(cols * sizeof(double));
  if (!x) return;
  XPRSgetcallbacksolution(cbprob, NULL, x, 0, cols - 1);

  printf("\nInteger solution found: %f\n", objval);
  for(i=0;i<cols;i++) printf(" x[%d] = %d\n", i, x[i]);
  free(x);
}
See also examples roundint.c, savesol.c.
Further information
1. This callback is useful if the user wants to retrieve the integer solution when it is found.
2. To retrieve the integer solution, use XPRSgetcallbacksolution, XPRSgetcallbackpresolvesolution or XPRSgetsolution.
3. This callback is called after a new integer solution was found by the Optimizer. Use a callback set by XPRSaddcbpreintsol in order to be notified before a new integer solution is accepted by the Optimizer, which allows for the new solution to be rejected.
4. For this callback attribute MIPINFEAS is set to -1 if the solution was found by a heuristic.
Related topics
XPRSremovecbintsol, XPRSaddcbpreintsol.

Parent Topic Console and Library Functions

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