DiagGaussObsModel.py 文件源码

def c_Diff(nu1, beta1, m1, kappa1,
           nu2, beta2, m2, kappa2):
    ''' Evaluate difference of cumulant functions c(params1) - c(params2)

    May be more numerically stable than directly using c_Func
    to find the difference.

    Returns
    -------
    diff : scalar real value of the difference in cumulant functions
    '''
    cDiff = - 0.5 * LOGTWO * (nu1 - nu2) \
        - gammaln(0.5 * nu1) + gammaln(0.5 * nu2) \
        + 0.5 * (np.log(kappa1) - np.log(kappa2)) \
        + 0.5 * (nu1 * np.log(beta1) - nu2 * np.log(beta2))
    return np.sum(cDiff)