Skip to content

Commit

Permalink
modify logic regression
Browse files Browse the repository at this point in the history
  • Loading branch information
endymecy committed May 31, 2016
1 parent b3828ff commit 42b1e4c
Showing 1 changed file with 2 additions and 2 deletions.
4 changes: 2 additions & 2 deletions 分类和回归/线性模型/逻辑回归/logic-regression.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@

  逻辑回归其实是在线性回归的基础上,套用了一个逻辑函数。上图的`g(z)`就是这个逻辑函数(或称为`Sigmoid`函数)。下面左图是一个线性的决策边界,右图是非线性的决策边界。

<div align="center"><img src="imgs/1.2.png" width = "780" height = "300" alt="1.2" align="center" /></div><br>
<div align="center"><img src="imgs/1.2.png" width = "700" height = "280" alt="1.2" align="center" /></div><br>

&emsp;&emsp;对于线性边界的情况,边界形式可以归纳为如下公式**(1)**:

Expand Down Expand Up @@ -46,7 +46,7 @@

&emsp;&emsp;对于`k`类的多分类问题,模型的权重`w = (w_1, w_2, ..., w_{K-1})`是一个矩阵,如果添加截距,矩阵的维度为`(K-1) * (N+1)`,否则为`(K-1) * N`。单个样本的目标函数的损失函数可以写成如下公式**(7)**的形式。

<div align="center"><img src="imgs/2.2.png" width = "720" height = "165" alt="2.2" align="center" /></div><br>
<div align="center"><img src="imgs/2.2.png" width = "720" height = "170" alt="2.2" align="center" /></div><br>

&emsp;&emsp;对损失函数求一阶导数,我们可以得到下面的公式**(8)**:

Expand Down

0 comments on commit 42b1e4c

Please sign in to comment.