factory.py 文件源码

def diagonal_mpa(entries, sites):
    """Returns an MPA with ``entries`` on the diagonal and zeros otherwise.

    :param numpy.ndarray entries: one-dimensional array
    :returns: :class:`~mpnum.mparray.MPArray` with rank ``len(entries)``.

    """
    assert sites > 0

    if entries.ndim != 1:
        raise NotImplementedError("Currently only supports diagonal MPA with "
                                  "one leg per site.")

    if sites < 2:
        return mp.MPArray.from_array(entries)

    ldim = len(entries)
    leftmost_ltens = np.eye(ldim).reshape((1, ldim, ldim))
    rightmost_ltens = np.diag(entries).reshape((ldim, ldim, 1))
    center_ltens = np.zeros((ldim,) * 3)
    np.fill_diagonal(center_ltens, 1)
    ltens = it.chain((leftmost_ltens,), it.repeat(center_ltens, sites - 2),
                     (rightmost_ltens,))

    return mp.MPArray(LocalTensors(ltens, cform=(sites - 1, sites)))


#########################
#  More physical stuff  #
#########################