int QSget_named_slack (QSprob p, const char *rowname, double *val)
/* p is an initialized QSprob, a handle to an existing LP problem  */
/* Get the slack value for the constraint r2.                      */

int rval;
double val;

rval = QSget_named_slack (p, "r2", &val);
if (rval) {
    fprintf (stderr, 
             "Could not get the slack value, error code %d\n", rval);
} else {
    printf ("Slack value = %.6f\n", val);
}