distributions.py 文件源码

def LogNormalDistribution(mean, std):
        if std == .0:
            return Distribution.ConstantDistribution(mean)
        var = std * std
        mean2 = mean * mean
        mu = np.log(mean) - (var/2)*(1/mean2)
        sigma = np.sqrt(var/mean2)
        dist = UncertainVariable(ss.lognorm(sigma, scale=np.exp(mu)))
        logging.debug('Distribution -- LogNormal: ({}, {})'.format(
            dist.mean, np.sqrt(dist.var)))
        return dist