XPRSiisstatus

Purpose

Returns statistics on the Irreducible Infeasible Sets (IIS) found so far by XPRSiisfirst ( IIS), XPRSiisnext ( IIS -n) or XPRSiisall ( IIS -a).

Synopsis

int XPRS_CC XPRSiisstatus(XPRSprob prob, int *iiscount, int rowsizes[], int colsizes[], double suminfeas[], int numinfeas[]);

Arguments

prob	The current problem.
iiscount	The number of IISs found so far.
rowsizes	Number of rows in the IISs.
colsizes	Number of bounds in the IISs.
suminfeas	The sum of infeasibilities in the IISs after the first phase simplex.
numinfeas	The number of infeasible variables in the IISs after the first phase simplex.

Example

This example first retrieves the number of IISs found so far, and then retrieves their main properties. Note that the arrays have size count+1, since the first index is reserved for the initial infeasible subset.

XPRSiisstatus(myprob,&count,NULL,NULL,NULL,NULL);
rowsizes  = malloc((count+1)*sizeof(int));
colsizes  = malloc((count+1)*sizeof(int));
suminfeas = malloc((count+1)*sizeof(double));
numinfeas = malloc((count+1)*sizeof(int));
XPRSiisstatus(myprob,&count,rowsizes,colsizes,suminfeas,numinfeas);

Further information

1. Calling IIS -s from the console has the same effect as this function.

2. All arrays should be of dimension iiscount+1. The arrays are 0 based, index 0 corresponding to the initial infeasible subproblem.

3. The arrays may be NULL if not required.

4. For the initial infeasible problem (at position 0) the subproblem size is returned (which may be different from the number of bounds), while for the IISs the number of bounds is returned (usually much smaller than the number of columns in the IIS).

5. Note that the values in suminfeas and numinfeas heavily depend on the actual basis where the simplex has stopped.

6. iiscount is set to -1 if the search for IISs has not yet started.

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XPRSiisstatus

XPRSiisstatus