# MathJax support for rendering equations

If I’m going to occasionally write posts about math (and that is the plan), I need the ability to render equations. It’s not a strict necessity; you can get pretty far by literally describing what it is that you’re trying to say. For example:

The Riemannian gradient over the compact Stiefel manifold of the Rayleigh quotient with respect to some square matrix and a given conformal subspace can be computed as the orthogonal complement with respect to a basis for that subspace of the product of said matrix and said basis.

However, though it may not be worth a thousand words, an equation in this case is worth approximately fifty words:

`<div>\$\$\nabla\ \textrm{RQ}_A(\textrm{colspan}(V)) = (I - VV^T)AV\$\$</div>`

Fortunately, there are more solutions for this than the last time I looked, circa 2007. And if you Google “math, latex and hugo” (as I did), you find the following on the official Hugo website: MathJax support in Hugo.

And so, because I’m a fan of test-driven development, I wrote up this post with a little math (i.e., the block math above) and this inline
SVD here: `$A v_i = u_i \sigma_i$`

. And because I hadn’t gone through the steps in the post above, it looked like shit
(i.e., the test failed):

But when you add in the steps from the article to add MathJax support to all pages (e.g., in the footer), it’s *mostly* good. My text editor (vim) still doesn’t understand the LaTeX subscript underscores in the markdown files:

But I can deal with that in a few ways: ignore it, or tell vim not to do syntax highlighting on markdown files (`set filetype`

). I’ll update this post if I find a better solution.
But in the meantime, I don’t have any excuse not to do math posts.

*Update*: MathJax pops up obnoxious loading/processing messages in the browser while it is loading. You can disable this by setting `messageStyle`

to `'none'`

, like so:

```
<script type="text/x-mathjax-config">
MathJax.Hub.Config({
messageStyle: 'none',
showProcessingMessages: false,
tex2jax: {
// tex2jax config...
}
});
</script>
```