int QSchange_coef (QSprob p, int rowindex, int colindex, double coef)

Use this function to change a single coefficient in the constraint matrix; it can be used to modify an existing non-zero coefficient or to add a new non-zero coefficient.

Note that the function assumes that both the row and column exist; use QSadd_row or QSadd_col if the coefficient introduces a new row or column.

/* Change the matrix coefficient in row 1, col 2, to 1.5   */

int rval = 0;

rval = QSchange_coef (p, 1, 2, 1.5);
if (rval) {
    fprintf (stderr, "could not change coef, error code %d\n", rval);
}