'The mass matrix of the system, augmented by the kinematic
differential equations.'

@property
def mass_matrix_full(self):

    if ((not self._fr) or (not self._frstar)):
        raise ValueError('Need    to    compute    Fr,    Fr*    first.')
    o = len(self.u)
    n = len(self.q)
    return self._k_kqdot.row_join(zeros(n, o)).col_join(zeros(o, n).row_join(self.mass_matrix))
