I'd like to render mathematical equations nicely in the browser. MathML seems like the right tool, but it's not supported everywhere.

# Exploring Ways to Get Math to the Web¶

Examples are based on Pandoc's math demo text.

## First Attempt¶

Write it and see what Pelican does without modification:

`$v(t) = v_0 + \frac{1}{2}at^2$`

Renders as:

$v(t) = v_0 + \frac{1}{2}at^2$

Unfortunately, Pelican doesn't know what to do with it, so I just get the plain text.

## Second Attempt¶

Embed an html fragment using Jinja include syntax. This would allow me to compile the latex into MathML using other tools, such as Pandoc.

Keeping the include syntax caused rendering problems elsewhere and didn't work, so it's not worth keeping.

## Third Attempt¶

Just to confirm things would work, I'm copying some raw MathML here from the
Pandoc example. I made one small edit to change the display from `inline`

to
`block`

.

With a little styling modification to the CSS, it'll actually work out nicely.
I'm just adding `10px`

of padding for now and I can come back to it later if
that doesn't work.

## Render it as an image¶

This would likely slow down the page loading with lots of images for math, but it could work. I'd also have to change how my image styling works slightly because I'd expect the math equations to be different proportions than the usual images taken with a camera.

This is promising, but I'd like to see if I can use web technologies to do better.

## Manual Scripting¶

One thing I'm considering is using some sort of automation to find and replace
Latex code with rendered MathML using some external tool. I could use an easily
matched regex (e.g. `![Math](.*)`

) and then strip the leading and trailing
parenthesis and substitute the middle section of the match with whatever MathML
rendering I get.

Now to figure out if I can do better than manually copying in MathML.

## Customizing Pelican¶

Pelican provides support for plugins that can be used to modify or replace how certain parts of the internals work. I think the easiest thing to do here would be to implement a new reader that interrupts the existing Markdown Reader (preferred, yay code re-use!) or borrows its implementation (taking inspiration from open source software, I should contribute it back).

I'm just going to say, their pretty short version of the Markdown reader in
their
docs
does not match the
source
which is noticeably more complicated. The `read`

function is pretty close
though.

To best leverage the existing code, I can either call something before the read function and then call the existing read function, or I can capture the output of the existing read and modify it. I'll need to do a little sleuthing to figure out what each looks like.

Time passes...

In the end, I decided to parse the HTML output of the original Markdown parser,
then find special `img`

tags with the alt text `LaTeX`

. From there, I edit that
tag in place to move the original LaTeX source to the alt text and render the
LaTeX into the child elements as MathML. This is effectively using some Python
libraries and Pelican to take the "Scripting" approach.

The end Markdown syntax looks like:

`![LaTeX](insert^{LaTeX}_{here})`

And rendered:

$$inser{t}_{here}^{LaTeX}$$

A more complicated example from the Pandoc set:

`![LaTeX](e^x = \sum_{n=0}^\infty \frac{x^n}{n!} = \lim_{n\rightarrow\infty} (1+x/n)^n)`

Rendered:

$${e}^{x}={\sum}_{n=0}^{\infty}\frac{{x}^{n}}{n!}=\underset{n\to \infty}{lim}{(1+x/n)}^{n}$$

Useful: Pelican source

Also Useful: Pelican plugin library

# But What about Unsupported Browsers?¶

I'm looking at you Chrome

I think the answer may involve using a Sympy viewer or a custom writer. If the custom reader updates metadata with the right information, the writer can write out custom image files.

Update 2020-05-02

The answer turned out to be a combination of both. The custom reader now generates PNG files that render the LaTeX. You can view the rendering by clicking on the equation.

$$\exists x\forall y(Rxy\equiv Ryx)$$