int QSadd_row (QSprob p, int cnt, int *rmatind, double *rmatval, 
    double rhs, char sense, const char *name)

The QSadd_row function provides a simpler interface than QSadd_rows for adding a single constraint to an existing LP, for example, the argument rhs is a double rather than an array of doubles (of length 1 when adding only a single constraint).

When specifying rmatval and rhs, it is important not to give any value larger in magnitude than QS_MAXDOUBLE (1e30). This restriction is due to the internal structures used in the QSopt solvers.

Note that when adding many constraints, it is more efficient to use QSadd_rows rather than repeated calls to QSadd_row, due to the internal data management in the QSopt library.

/* Assume p is initialized to the problem in the QSload_prob example. */
/* Add the constraint 0.5x + 2.0y + 4.0z >= 6.0 to the LP.            */

int rval;
int rmatind[3] = { 0, 1, 2 };
int rmatval[3] = { 0.5, 2.0, 4.0 };

rval = QSadd_row (p, 2, rmatind, rmatval, 6.0, 'G', (const char *) NULL);
if (rval) {
    fprintf (stderr, "QSadd_row failed with return code %d\n", rval);
}