def calc_delta_c(c200):
top = (<NUM_LIT> / <NUM_LIT>) * c200**<NUM_LIT><EOL>bottom = np.log(<NUM_LIT:1.> + c200) - (c200 / (<NUM_LIT:1.> + c200))<EOL>return (top / bottom)<EOL>
Calculate characteristic overdensity from concentration.

    Parameters
    ----------
    c200 : ndarray or float
        Cluster concentration parameter.

    Returns
    ----------
    ndarray or float
        Cluster characteristic overdensity, of same type as c200.