Math test

Inline math should render: $E = mc^2$, $\nabla \cdot \mathbf{E} = \rho/\varepsilon_0$.

Display math should render centered:

$$\int_{-\infty}^{\infty} e^{-x^2}\, dx = \sqrt{\pi}$$

A matrix:

$$A = \begin{bmatrix} a & b \\ c & d \end{bmatrix}, \quad \det(A) = ad - bc$$

A sum with a fraction:

$$\sum_{n=1}^{\infty} \frac{1}{n^2} = \frac{\pi^2}{6}$$