test

$$sum_{i = 0}^{infty} frac{1}{i^2} = frac{pi^2}{6}​$$

1
2

def (n):
    return 1 if n <= 1 else n * fac(n - 1)

Here we define a function def fac(n).

Single line mathjax $a[x][?]$, $b_i * a[x][?]$ .

This will be error : $a * b * c * d$.

You must use $a times b times c times d$ or $a cdot bcdot ccdot d$.

This is because in markdown * will be treated as ‘emphy’.

$$begin{align} F_{i, j} = & a_1 + a_2 & a_3 + a_4 end{align}​$$

$$A = begin{bmatrix} vec{a_1} vec{a_2} ldots vec{a_n}end{bmatrix}​$$

Test.