def c2c2DMO(X, choice="NIHAO"):
    """
    The ratio between the baryon-influenced concentration c_-2 and the
    dark-matter-only c_-2, as a function of the stellar-to-halo-mass
    ratio, based on simulation results.

    Syntax:

        c2c2DMO(X,choice='NIHAO')

    where

        X: M_star / M_vir (float or array)
        choice: choice of halo response --
            'NIHAO' (default, Tollet+16, mimicking strong core formation)
            'APOSTLE' (Bose+19, mimicking no core formation)
    """
    if choice == "NIHAO":
        # return 1. + 227.*X**1.45 - 0.567*X**0.131 # <<< Freundlich+20
        return 1.2 + 227.0 * X ** 1.45 - X ** 0.131  # <<< test
    elif choice == "APOSTLE":
        return 1.0 + 227.0 * X ** 1.45