Initializing help system before first use

XPRSaddcbslpitervar

Purpose
Add a user callback to be called after each column has been tested for convergence
Topic areas
Callback, SLP, SLP-convergence
Synopsis
int XPRS_CC XPRSaddcbslpitervar(XPRSprob prob, int (XPRS_CC *slpitervar) (XPRSprob cbprob, void *cbdata, int col), void *data, int priority);
Arguments
prob 
The current problem.
slpitervar 
The function to be called after each column has been tested for convergence. slpitervar returns an integer value. The return value is interpreted as a convergence status. The possible values are:
< 0 
The variable has not converged;
0 
Keep the internal convergence status;
1 to 10 
The column has converged on a system-defined convergence criterion (these values should not normally be returned);
> 10 
The variable has converged on user criteria.
cbprob 
The problem passed to the callback function.
cbdata 
The user-defined object passed as data to XPRSaddcbslpitervar.
col 
The number of the column which has been tested for convergence.
data 
Address of a user-defined object, which can be used for any purpose by the function. data is passed to slpitervar 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 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;
XPRSaddcbslpitervar(prob, CBIterVar, &Important, 0);
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(XPRSprob MyProb, void *Obj, int iCol) {
  int *Important, Converged;
  Important = *(int **) Obj;
  XPRSalltype alltype;
  XPRSslpgetcolinfo(MyProb, XSLP_COLINFO_CONVERGENCESTATUS, iCol, &alltype);
  if (alltype.value.integer != 0) return 0;
  if (!Important[iCol]) return 99;
  return -1;
}
The data 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.
Related topics
XPRSaddcbslpiterend, XPRSaddcbslpiterstart XPRSremovecbslpitervar

Parent Topic Library functions

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