def _limb_darkened_profile(limb_dark_law, LDCs, mu):
    """Returns limb-darkened flux

    Args:
        limb_dark_law (str): 'quadratic'
        LDCs (numpy array): limb-darkening coefficients
            Must have two elements for 'quadratic'
        mu (numpy array): cos of the angle between the line-of-sight and the
            normal to a grid element of the host's surface

    Returns:
        numpy array: normalized flux profile

    """
    if limb_dark_law == 'quadratic' and len(LDCs) == 2:
        return 1.0 - LDCs[0] * (1.0 - mu) - LDCs[1] * (1.0 - mu) * (1.0 - mu)
    else:
        raise ValueError('Only quadratic limb-darkening law allowed, ' +
            'which requires two coefficients!')
