def chromatic_induction_factors(n):
    """
    Returns the chromatic induction factors :math:`N_{bb}` and :math:`N_{cb}`.

    Parameters
    ----------
    n : numeric
        Function of the luminance factor of the background :math:`n`.

    Returns
    -------
    tuple
        Chromatic induction factors :math:`N_{bb}` and :math:`N_{cb}`.

    Examples
    --------
    >>> chromatic_induction_factors(0.2)  # doctest: +ELLIPSIS
    (1.0003040..., 1.0003040...)
    """

    N_bb = N_cb = 0.725 * (1 / n) ** 0.2
    return N_bb, N_cb