test file for mathjax support

Thanks for @xolmon

Superscript

```math
x^2
```

Subscript

```math
x_2
```

Relation between energy and mass

```math
E=mc^2
```

Fraction

```mathjax
\frac{1}{1-x^2}
```

plus/minus and sqrt, over

```mathjax
x = {-b \pm \sqrt{b^2-4ac} \over 2a}
```

Pi

```math
\pi
```

Vector

```math
\vec{a} = (a_1, a_2, \cdots, a_n)
```

Array

```mathjax
A = \left(
    \begin{array}{ccc}
      1 & 2 & 3 \\
      4 & 5 & 6 \\
      7 & 8 & 9
    \end{array}
  \right)\\
A^T
```

Sum

```mathjax
\sum_{n=1}^{100} x^2 \\
```

```mathjax
\sum_{n=1}^\infty\frac{1}{n^2}=\frac1{1^2}+\frac1{2^2}+\frac1{3^2}+\frac1{4^2}+\frac1{5^2}+\cdots
```

Differential

```math
\frac{(d^2y)}{dx^2}
```

Integral

```math
\int f(x)dx
```

```math
\int_1^\infty \frac{1}{x^2}dx
```

Limit

```math
\lim_{x \to \infty} f(x)
```

angle

```math
180^\circ
```

Logarithm

```math
log_e(x)
```

Inequality

```math
x\neq 0
```

```math
1 < x
```

```math
1 \leq x
```

```math
\alpha \sim 1
```

```math
\beta \simeq 0
```

```math
\gamma \approx 10
```

Euler's formula

```math
e^{i\theta}=\cos\theta+i\sin\theta
```