student_t.py 文件源码

def _cdf(self, x):
    # Take Abs(scale) to make subsequent where work correctly.
    y = (x - self.loc) / math_ops.abs(self.scale)
    x_t = self.df / (y**2. + self.df)
    neg_cdf = 0.5 * math_ops.betainc(0.5 * self.df, 0.5, x_t)
    return array_ops.where(math_ops.less(y, 0.), neg_cdf, 1. - neg_cdf)