def mlo(i, j):  # pragma: no cover
    """Auxiliary function for La Budde's algorithm.
    See `arXiv:1104.3769 <https://arxiv.org/abs/1104.3769v1>`_.

    .. note::

        The La Budde paper uses indices that start counting at 1 so this function
        lowers them to start counting at 0.

    Args:
        matrix (array): upper-Hessenberg matrix
        i (int): row
        j (int): column

    Returns:
        int: linear matrix index lowered by 1
    """
    return tuple((i - 1, j - 1))