Return the inverse transformation of a m4x4 transformation
    :param mat: A m4x4 transform
    :return: inv_transform inverse of the tranformation

def inverse_m4x4_transform(mat):
    """
    Return the inverse transformation of a m4x4 transformation
    :param mat: A m4x4 transform
    :return: inv_transform inverse of the tranformation
    """
    inv_transform = zeros((4, 4))
    rot = mat[:-1, :-1].T
    inv_transform[:-1, :-1] = rot
    inv_transform[:-1, -1] = dot(-rot, mat[:-1, -1])
    inv_transform[-1, -1] = 1
    return inv_transform