latex display mode $$ (multi line mode) cannot be recognized

[yubaoliu]

Hello,

I want to use $$ too, because my equation is very long sometimes and I want to keep a good format.

For example: $$ a \times b = \begin{bmatrix} i & j & k \ a_1 & a_2 & a_3 \ b_1 & b_2 & b_3 \end{bmatrix}

\begin{bmatrix} a_2 b_3 - a_3 b_2 \ a_3 b_1 - a_1 b_3 \ a_1 b_2 - a_2 b_1 \end{bmatrix}

\begin{bmatrix} 0 & -a_3 & a_2 \ a_3 & 0 & -a_1 \ -a_2 & a_1 & 0 \end{bmatrix} b \triangleq a^\hat{} b $$

My question is how to render $$. I know the equation is rendered use googleapi.

[TeX Mathematical Formulae Support: ]

1. How to customize it to support $$ ?
2. If it is impossible to implement, how to let Markdownit ignore $$, so that I can use mathjax to parse it?

Thanks