第二次转移博客

$ \sqrt{\phi} $

$${1+1=2}$$ $${\fac 1}$$

Simple inline $ a = b + c $

$$\frac{\partial u}{\partial t} = h^2 \left( \frac{\partial^2 u}{\partial x^2} + \frac{\partial^2 u}{\partial y^2} + \frac{\partial^2 u}{\partial z^2}\right)$$