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XPRSaddcbslpintsol

Purpose
Add a user callback to be called during MISLP when an integer solution is obtained
Topic areas
Callback, MISLP
Synopsis
int XPRS_CC XPRSaddcbslpintsol(XPRSprob prob, int (XPRS_CC *slpintsol) (XPRSprob cbprob, void *cbdata), void *data, int priority);
Arguments
prob 
The current problem.
slpintsol 
The function to be called when an integer solution is obtained. slpintsol returns an integer value. At present, the return value is ignored.
cbprob 
The problem passed to the callback function.
cbdata 
The user-defined object passed as data to XPRSaddcbslpintsol.
data 
Address of a user-defined object, which can be used for any purpose by the function. data is passed to slpintsol as cbdata.
priority 
An integer that determines the order in which callbacks of this type 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 sets up a callback to be executed whenever an integer solution is found during MISLP: 
double *cSol;
int nInputCol;
XPRSgetintattrib(prob, XPRS_INPUTCOLS, &nInputCol);
cSol = (double*)malloc(nInputCol * sizeof(double));
XPRSaddcbslpintsol(prob, CBIntSol, &cSol, 0);
The following sample callback function saves the solution values for the integer solution just found: 
int XPRS_CC CBIntSol(XPRSprob MyProb, void *Obj) {
  XPRSprob MyProb;
  int nInputCol;
  int solStatus;
  double *cSol;

  cSol = * (double **) Obj;
  XPRSgetintattrib(MyProb, XPRS_INPUTCOLS, &nInputCol);
  XPRSgetsolution(MyProb, &solStatus, cSol, 0, nInputCol-1);
  return 0;
}
The data argument is used here to hold the address of the array cSol.
Further information
This callback must be used during MISLP instead of the XPRSsetcbintsol callback which is used for MIP problems.
Further information
Note that for SLP-MIP-SLP (see XSLP_MIPALGORITHM), the slpintsol callback will only be fired once after the second SLP solve terminated, in which case the solution can also only be queried via XPRSgetsolution but not via XPRSgetlpsol (unless postsolve is disabled).
Related topics
XSLPsetcboptnode, XPRSremovecbslpintsol

Parent Topic Library functions

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