Box-Muller算法
当x和y是两个独立且服从（0，1）均匀分布的随机变量时，有：
Z1 = cos(2\pi x)*\sqrt{-2ln(1-y))} Z2 = sin(2\pi x)*\sqrt{-2ln(1-y))} Z1和Z2独立且服从标准正态分布，当带入均值和方差时:
Z = Z1(Z2)*\sigma +\mu
Hello World
Welcome to Hexo! This is your very first post. Check documentation for more info. If you get any problems when using Hexo, you can find the answer in troubleshooting or you can ask me on GitHub.