mparray.py 文件源码

def norm(mpa):
    """Computes the norm (Hilbert space norm for MPS, Frobenius norm for MPO)
    of the matrix product operator. In contrast to ``mparray.inner``, this can
    take advantage of the canonicalization

    WARNING This also changes the MPA inplace by normalizing.

    :param mpa: MPArray
    :returns: l2-norm of that array

    """
    mpa.canonicalize()
    current_lcanon, current_rcanon = mpa.canonical_form

    if current_rcanon == 1:
        return np.linalg.norm(mpa.lt[0])
    elif current_lcanon == len(mpa) - 1:
        return np.linalg.norm(mpa.lt[-1])
    else:
        raise ValueError("Normalization error in MPArray.norm")