Note: this is the first post under a new tag called TIL or “today I learned”. These are shorter format posts that lower the barrier to blogging and capture a mini piece of learning. The idea for TILs has been inspired by Simon Willison’s own TIL posts.
It’s really useful to have an RSS feed associated with a blog so that people can automatically pick up new posts. A lot of blogging technology (including Quarto and Jekyll) automatically creates these feeds at a URL called <website name>/index.xml, or similar, relative to the root of your website.
But I kept finding a problem with generating these feeds: either they did not generate at all or they were corrupted and unreadable.
I use a lot of latex in my blog posts. You can do this inline using dollar signs or as a display equation using double dollar signs in a separate paragraph. So
$$
{\displaystyle F_{ij}=G\cdot {\frac {M_{i}M_{j}}{D_{ij}}}.}
$$becomes
\[ {\displaystyle F_{ij}=G\cdot {\frac {M_{i}M_{j}}{D_{ij}}}.} \]
So far so good. But, when you’re putting latex in a code block—for example, when you’re demonstrating how to add an equation to a chart in matplotlib in code—the string with latex in can crash the automatic blog RSS feed generator.
An example of the kind of string in a blog post that causes the problem is:
```python
ax.set_xlabel(r"$e^\frac{-x^2}{2}$")
```except with the " characters replaced with ' because, ironically, I can’t write this string without breaking the feed again.
The solution—as you can probably guess by now—is to use " instead of ' for literal strings with latex in them in code blocks.
And, if you’re digesting this via an RSS feed, you’ll know it’s worked!