def incremental_value(self, slip_moment, mmax, mag_value, bbar, dbar):
        """
        Returns the incremental rate with Mmax = Mag_value
        """
        delta_m = mmax - mag_value
        a_3 = self._get_a3(bbar, dbar, slip_moment, mmax)
        return a_3 * bbar * (np.exp(bbar * delta_m) - 1.0) * (delta_m > 0.0)