https://blog.youkuaiyun.com/bitcarmanlee/article/details/52662518
https://blog.youkuaiyun.com/mucai1/article/details/85242098
https://blog.youkuaiyun.com/qq_27245709/article/details/91469688
奇异值分解
https://www.cnblogs.com/endlesscoding/p/10033527.html