1.协方差含义
https://www.zhihu.com/question/20852004
2.金融领域应用
https://zhuanlan.zhihu.com/p/38320827
https://zhuanlan.zhihu.com/p/38321845
https://zhuanlan.zhihu.com/p/38322333
https://zhuanlan.zhihu.com/p/38322638
3.deepAR
https://www.bilibili.com/video/BV1xT4y1g7eC?from=search&seid=16750258316438926531
https://zhuanlan.zhihu.com/p/201030350
https://www.jianshu.com/p/8a900b9ad3d3
3.平稳
https://www.zhihu.com/question/29128649/answer/112180602
ARMA
https://www.bilibili.com/video/BV15Q4y1K7Ga?p=58
ARMA ARIMA
https://www.math.pku.edu.cn/teachers/lidf/course/atsa/atsanotes/html/_atsanotes/atsa-arima.html
指数平滑等
https://otexts.com/fppcn/ses.html
https://blog.csdn.net/qq_29831163/article/details/89440215