def METHOD_NAME(s, a, b, R, df):
    sqrt_df = np.sqrt(df+0.5)
    ret = chi_logpdf(s,df)
    ret += np_log(mvstdnormcdf(s*a/sqrt_df, s*b/sqrt_df, R,
                                         maxpts=1000000, abseps=1e-6))
    ret = np_exp(ret)
    return ret