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XSLPsetcbitervarF

Purpose

Set a user callback to be called after each column has been tested for convergence

Synopsis

int XPRS_CC XSLPsetcbitervarF(XSLPprob Prob, 
               int (XPRS_CC *UserFunc) (XSLPprob myProb, void *myObject, int *ColIndex), 
               void *Object);

Arguments

Prob  

The current SLP problem.

UserFunc  

The function to be called after each column has been tested for convergence. UserFunc returns an integer value. The return value is interpreted as a convergence status. The possible values are:

< 0	The variable has not converged;
0	The convergence status of the variable is unchanged;
1 to 9	The column has converged on a system-defined convergence criterion (these values should not normally be returned);
> 9	The variable has converged on user criteria.

myProb  

The problem passed to the callback function.

myObject  

The user-defined object passed as Object to XSLPsetcbitervarF.

ColIndex  

Address of an integer holding the number of the column which has been tested for convergence. The column number respects the setting of XPRS_CSTYLE.

Object  

Address of a user-defined object, which can be used for any purpose by the function. Object is passed to UserFunc as myObject.

Example

The following example sets up a callback to be executed after each variable has been tested for convergence. The user object Important is an integer array which has already been set up and holds a flag for each variable indicating whether it is important that it converges.

int *Important;
XSLPsetcbitervarF(Prob, CBIterVar, &Important);

The following sample callback function tests if the variable is already converged. If not, then it checks if the variable is important. If it is not important, the function returns a convergence status of 99.

int XPRS_CC CBIterVar(XSLPprob MyProb, void *Obj, int *pCol) {
  int *Important, Converged, iCol;
  Important = *(int **) Obj;
  iCol = *pCol;
  XSLPgetvar(MyProb, iCol, NULL, NULL, NULL, 
             NULL, NULL, NULL, NULL, 
             NULL, NULL, &Converged, NULL,
             NULL, NULL, NULL, NULL);
  if (Converged) return 0;
  if (!Important[iCol]) return 99;
  return -1;
}

The Object argument is used here to hold the address of the array Important.

Further information

This callback can be used after each variable has been checked for convergence, and allows the convergence status to be reset if required.

XSLPsetcbitervarF is identical to XSLPsetcbitervar except that the column number is passed by reference rather than by value.