汇总EM算法的讲解

https://blog.csdn.net/v_JULY_v/article/details/81708386

https://blog.csdn.net/zouxy09/article/details/8537620

https://www.cnblogs.com/mindpuzzle/archive/2013/04/05/2998746.html

https://www.cnblogs.com/pinard/p/6912636.html