def calc_flux_intg_ratio_from_mags(mag_1, mag_2):
    """Calculate the ratio of integrated fluxes from two magnitudes.
    
    Parameters
    ----------
    mag_1 : float
        Magnitude of source 1. Unit is magnitudes.
    mag_2 : float
        Magnitude of source 2. Unit is magnitudes.
        
    Returns
    -------
    flux_intg_ratio : float
        Ratio of fluxes for sources 1 and 2 as flux_1 / flux_2. Unitless.
    
    Notes
    -----
    flux_1 / flux_2 = 100**((mag_2 - mag_1)/5)
    From equation 3.3 in section 3.2 of [1]_.
    
    References
    ----------
    .. [1] Carroll and Ostlie, 2007, An Introduction to Modern Astrophysics
    
    """
    flux_intg_ratio = 100.0 ** ((mag_2 - mag_1) / 5.0)
    return flux_intg_ratio
