def METHOD_NAME(C, ctx):
    mean = (C['d0'] + _get_source_term_duration(C, ctx) +
            _get_path_term_duration(C, ctx) + _get_site_term_duration(C, ctx))
    phi = np.sqrt(C['phi']**2 + C['phis2s']**2)
    tau = C['tau']
    sigma = np.sqrt(C['phi']**2 + C['tau']**2 + C['phis2s']**2)
    return mean, sigma, tau, phi