Testing

In what follows we input math formula via $\LaTeX$ syntax:

\[\mathcal{L} = i \overline{\Psi} \gamma^\mu D_\mu \Psi\]

and

\[\sigma_1 = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} , \sigma_2 = \begin{pmatrix} 0 & -i \\ i & 0 \end{pmatrix} , \sigma_3 = \begin{pmatrix} 1 & 0 \\ 0 & -1 \end{pmatrix}\]

And this is inline math: $F = m f(a)$. All seem nicely done.

And this is inline codes: import numpy, and code fence:

import os
os.listdir('/')
print('Hello, world!')

All these allows me to post some technical articles.