(转载请注明出处:http://blog.csdn.net/buptgshengod)
1.感受
这一节课Andrew讲的是监督学习应用中的梯度下降方法(Supervised-Learning,grading and descent)。 公式比较多,不过还比较基础,主要是一些矩阵论的应用。2.笔记
Grading and descent 主要用到的就是一个回归的思路。整体的流程见下图。X1,X2....表示的不同的特征,经过算法H的变化,输出Y1,Y2......。可以用公式表达为
![斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降 斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降](https://image.shishitao.com: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.jpg?w=700&webp=1)
![斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降 斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降](https://image.shishitao.com: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%3D%3D.jpg?w=700&webp=1)
![斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降 斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降](https://image.shishitao.com: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%3D%3D.jpg?w=700&webp=1)
![斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降 斯坦福机器学习公开课学习笔记(2)—监督学习 梯度下降](https://image.shishitao.com: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%3D%3D.jpg?w=700&webp=1)
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(转载请注明出处:http://blog.csdn.net/buptgshengod)