def add_jac(self, m, val, row, col):
        """Add tuples (val, row, col) to the Jacobian matrix ``m``

        Implemented in numpy.arrays for temporary storage.
        """
        assert m in ('Fx', 'Fy', 'Gx', 'Gy', 'Fx0', 'Fy0', 'Gx0', 'Gy0'), \
            'Wrong Jacobian matrix name <{0}>'.format(m)

        if isinstance(val, (int, float)):
            val = val * ones(len(row), 1)

        self._temp[m]['I'] = matrix([self._temp[m]['I'], matrix(row)])
        self._temp[m]['J'] = matrix([self._temp[m]['J'], matrix(col)])
        self._temp[m]['V'] = matrix([self._temp[m]['V'], matrix(val)])