### 测试math-plugin

## Inline

Simple inline \(a = b + c\).

This equation \(\cos 2\theta = \cos^2 \theta - \sin^2 \theta = 2 \cos^2 \theta - 1 \) is inline.

## Block

$$\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)$$