def METHOD_NAME(xs, ys, zs, M):
    """
    Transform the points by the inverse of the projection matrix *M*.
    """
    iM = linalg.inv(M)
    vec = _vec_pad_ones(xs, ys, zs)
    vecr = np.dot(iM, vec)
    try:
        vecr = vecr / vecr[3]
    except OverflowError:
        pass
    return vecr[0], vecr[1], vecr[2]