def exposure_index_values(H_a):
    """
    Computes the exposure index values :math:`I_{EI}` from given focal plane
    exposure :math:`H_a`.

    Parameters
    ----------
    H_a : array_like
        Focal plane exposure :math:`H_a`.

    Returns
    -------
    ndarray
        Exposure index values :math:`I_{EI}`.

    References
    ----------
    :cite:`ISO2006`

    Examples
    --------
    >>> exposure_index_values(0.1628937086212269)  # doctest: +ELLIPSIS
    61.3897251...
    """
    return 10 / H_a
