网址

• 正则表达式: http://www.xiaoleilu.com/regex-guide/
• pdf https://smallpdf.com
• ML https://developers.google.cn/machine-learning/crash-course/prereqs-and-prework
• bias variance :https://liam0205.me/2017/03/25/bias-variance-tradeoff/
• svm 推导http://blog.sina.com.cn/s/blog_4298002e010144k8.html
• bp http://www.cnblogs.com/biaoyu/p/4591304.html