How to add LaTex formula to a Markdown

A hack for showing LaTeX formulas in GitHub markdown.md

Fork from: https://gist.github.com/a-rodin/fef3f543412d6e1ec5b6cf55bf197d7b

Problem

A lot of GitHub projects need to have pretty math formulas in READMEs, wikis or other markdown pages. The desired approach would be to just write inline LaTeX-style formulas like this:

$e^{i \pi} = -1$

Unfortunately, GitHub does not support inline formulas. The issue is tracked here.

Investigation

However, it does support them in Jupyter notebooks, scroll below to see an example. One might question how does it work in notebooks. It turns out that instead of relying on MathJax as nbviewer does, GitHub's notebooks renderer converts inline math to images with source URLs that look like this:

https://render.githubusercontent.com/render/math?math=e%5E%7Bi%20%5Cpi%7D%20%3D%20-1&mode=inline

Inspecting the URL, it is possible to notice that:

1. The &mode=inline part is not required, the URL still returns the same image without it:

   https://render.githubusercontent.com/render/math?math=e%5E%7Bi%20%5Cpi%7D%20%3D%20-1.

2. Modern browsers encode URLs automatically, thus this link would work as well:

   https://render.githubusercontent.com/render/math?math=e^{i \pi} = -1.

Solution

So the solution would be to insert this code in Markdown files:

<img src="https://render.githubusercontent.com/render/math?math=e^{i \pi} = -1">

and such an image would be rendered as .

This is more clumsy than just $e^{i \pi} = -1$, but it is still possible to write the formula by hand directly to the Markdown file this way.

Note that this syntax for image insertion would not work because the URL contains spaces:

![formula](https://render.githubusercontent.com/render/math?math=e^{i \pi} = -1)

Addition from 2019-10-30

I made a small app that allows to generate Markdown code from LaTeX using the method described above automatically.

notebook.ipynb

Alternatively, you can check out xhub. It's a browser extension I wrote that loads KaTeX into GitHub pages and let's you you math super easily in Markdown:

Display math:
```math
e^{i\pi} + 1 = 0
```
and line math $`a^2 + b^2 = c^2`$.

The math color is always text-color, so it works on light and dark backgrounds alike.

@nschloe Nice, but is there any alternative for Firefox?

@rffontenelle Not right now, but I might add it once Firefox has Manifest v3 support (see here and here).