Improve MathJax support by enabling $$ for math equations

[azerupi]

Currently, Mathjax is a little akward to use because we only support the \( ... \) and \[ ... \]method to indicate inline and block equations respectively. On top of that, backslashes need to be escaped so that the markdown parser doesn't remove them. Thus, equations need to be written like:

\\[ \mu = \frac{1}{N} \sum_{i=0} x_i \\]

So when mathjax support is enabled in the configuration, it would be great to add a preprocessor that rewrites the \[ ... \] forms to \\[ ... \\] and add support for the $$ ... $$ math delimiters.

[subthedubdub]

Couldn't this be implemented entirely in JavaScript (see the MathJax Docs)?

[azerupi]

Ah thanks for reminding me, I forgot the most important part of this issue!

Currently, math expressions will collide with markdown syntax. If you write a*b*c=d the markdown parser will emphasise b, which is not what we want.

So to make mathjax fully usable, we need to preprocess the equations and replace it with something that will be skipped by the markdown parser. The solution in my first post will therefore not work.

What I propose is to wrap the math equations with html tags. For inline <span class="inline-math">...</span> and for blocks <div class="math"></div>. The markdown parser will recognise this as raw HTML and will leave it as is.

[dvberkel]

I would like to look into this. Will start a branch and send in a WIP pull request

[brendanzab]

I'm wondering if it would be better to switch to using code-fences for embedded markup languages, as suggested in this thread on the CommonMark forums, eg:

```{latex}
\begin{tikzpicture}
\node[inner sep=0pt] (russell) at (0,0)
    {\includegraphics[width=.25\textwidth]{bertrand_russell.jpg}};
\node[inner sep=0pt] (whitehead) at (5,-6)
    {\includegraphics[width=.25\textwidth]{alfred_north_whitehead.jpg}};
\draw[<->,thick] (russell.south east) -- (whitehead.north west)
    node[midway,fill=white] {Principia Mathematica};
\end{tikzpicture}
```

This would also have the advantage of making the github previews look much nicer. We might have to wait for this to go through the pipeline of standardization though. :/