机器学习爱好者 -- 翻译吴恩达老师的机器学习课程字幕
http://www.ai-start.com/
https://zhuanlan.zhihu.com/fengdu78
https://github.com/fengdu78/Coursera-ML-AndrewNg-Notes
文档PDF https://github.com/fengdu78/Coursera-ML-AndrewNg-Notes/blob/master/%E6%9C%BA%E5%99%A8%E5%AD%A6%E4%B9%A0%E4%B8%AA%E4%BA%BA%E7%AC%94%E8%AE%B0%E5%AE%8C%E6%95%B4%E7%89%88v5.34-A4%E6%89%93%E5%8D%B0%E7%89%88.pdf
