在线LaTex网址：http://www.codecogs.com/latex/eqneditor.php
使用latex编辑公式，记录：
L = -\frac{1}{m} \sum_{i=1}^{m} \log \left ( \frac{\exp (\left \| x_{i} \right \| \cos (\theta_{y_{i}}))}{\exp (\left \| x_{i} \right \| \cos (\theta_{y_{i}})) + \sum_{j=1,j\neq y_{i}}^{n}\exp (\left \| x_{i} \right \| \cos (\theta_{y_{i}})) } \right )
L = -\frac{1}{m} \sum_{i=1}^{m} \log \left ( \frac{\exp (s\cos (\theta_{y_{i}}+m))
}{\exp (s\cos (\theta_{y_{i}}+m))
+ \sum_{j=1,j\neq y_{i}}^{n}\exp (s\cos (\theta_{j})) } \right )
L = -\frac{1}{m} \sum_{i=1}^{m}log(\frac{exp(W_{T}^{y_{i}}x_{i}+b_{y_{i}})}{\sum_{j=1}^{n}exp(W_{T}^{y_{i}}x_{i}+b_{y_{i}})})