测试

$ 18+15 $

$ x^2 $

$ f $

$$\begin{equation}
e=mc^2
\end{equation}$$

\[sin^2\theta + cos^2\theta = 1\]

$ H( X ) =-_{i=1}^n{p( x_i ) p( x_i )}$

\[ H\left( X \right) =-\sum_{i=1}^n{p\left( x_i \right) \log p\left( x_i \right)} \] \[ H\left( X \right) =-\sum_{i=1}^n{p\left( x_i \right) \log p\left( x_i \right)} \]