def calc_flux_rad_ratio_from_light(light_oc, light_tr, light_ref=1.0):
    """Calculate ratio of the radiative fluxes of the smaller star to greater star
    from their light levels  during occultation and transit.
    Assumes L \\propto r^2, no limb darkening.
    
    Parameters
    ----------
    light_oc : float
        Light level during occultation (primary eclipse). Light level is the average
        of the flat region at the bottom of one of the eclipse minima. The event is
        a total eclipse of the star with the smaller radius.
    light_tr : float
        Light level during transit (secondary eclipse). Light level is the average
        of the rounded region at the bottom of one of the eclipse minima. The event is
        an annular eclipse of the star with the larger radius.
    light_ref : {1.0}, float, optional
        Reference for light levels outside of eclipse. Typically total system light is normalized to 1.0.
        
    Returns
    -------
    flux_rad_ratio : float
        Ratio of radiative fluxes of smaller star to greater star.
        flux_rad_ratio = flux_rad_s / flux_rad_g

    Notes
    -----
    flux_rad_ratio = flux_rad_s / flux_rad_g
                   = (light_ref - light_oc) / (light_ref - light_tr)
    From equation 7.10 in section 7.3 of [1]_
    
    References
    ----------
    .. [1] Carroll and Ostlie, 2007, An Introduction to Modern Astrophysics
    
    """
    flux_rad_ratio = (light_ref - light_oc) / (light_ref - light_tr)
    return flux_rad_ratio
