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# XSLPsetcbintsol, XPRSsetcbslpintsol

Purpose
Set a user callback to be called during MISLP when an integer solution is obtained
Topic areas
Callback, MISLP
Synopsis
`int XPRS_CC XSLPsetcbintsol(XSLPprob prob, int (XPRS_CC *intsol) (XSLPprob cbprob, void *cbdata), void *data);`
Arguments

prob | The current SLP problem.
intsol | The function to be called when an integer solution is obtained. intsol 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 XSLPsetcbintsol.
data | A user-defined object, which can be used for any purpose by the function. data is passed to intsol as cbdata.

Example
The following example sets up a callback to be executed whenever an integer solution is found during MISLP:

    double *cSol;
    int nInputCol;
    XPRSgetintattrib(xprob, XPRS_INPUTCOLS, &nInputCol);
    cSol = (double*)malloc(nInputCol * sizeof(double));
    XSLPsetcbintsol(prob, CBIntSol, &cSol);

The following sample callback function saves the solution values for the integer solution just found:

    int XPRS_CC CBIntSol(XSLPprob MyProb, void *Obj) {
      XPRSprob xprob;
      int nInputCol;
      int solStatus;
      double *cSol;

      cSol = * (double **) Obj;
      XSLPgetptrattrib(MyProb, XSLP_XPRSPROBLEM, &xprob);
      XPRSgetintattrib(xprob, XPRS_INPUTCOLS, &nInputCol);
      XPRSgetsolution(xprob, &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 intsol callback will only be fired once after the second SLP solve terminated, in which case the solution can also only be queried via XPRSgetsolution or XSLPgetslpsol but not via XPRSgetlpsol (unless postsolve is disabled).
Related topics
XSLPsetcboptnode, XSLPsetcbprenode
Parent Topic Library functions and the programming interface

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