This blog has my random thoughts; game-related posts go here.

## Emacs org-mode and KaTeX

Emacs org-mode can handle LaTeX math, and exports it to HTML using MathJax. On my pages I have been using KaTeX instead of MathJax. It loads faster but doesn't support as many features. Org mode doesn't have direct support for KaTeX but for the simple things I do on my pages, I can redirect MathJax to KaTeX using KaTeX autorender:

(setq org-html-mathjax-template
<script defer=\"defer\" src=\"https://cdn.jsdelivr.net/npm/katex@0.10.0/dist/katex.min.js\" integrity=\"sha384-K3vbOmF2BtaVai+Qk37uypf7VrgBubhQreNQe9aGsz9lB63dIFiQVlJbr92dw2Lx\" crossorigin=\"anonymous\"></script>
<script defer=\"defer\" src=\"https://cdn.jsdelivr.net/npm/katex@0.10.0/dist/contrib/auto-render.min.js\" integrity=\"sha384-kmZOZB5ObwgQnS/DuDg6TScgOiWWBiVt0plIRkZCmE6rDZGrEOQeHM5PcHi+nyqe\" crossorigin=\"anonymous\" onload=\"renderMathInElement(document.body);\"></script>")


(it looks ugly but it's straight from the KaTeX autorender page, but with quotes backslashed)

This seems to work on the small tests I've done so far.

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## Emacs: prettier tabbar

Back in 2007 I posted that I was going to try buffer tabs for Emacs. At the time I wasn't sure if I'd like it. People told me that there's no point in displaying them visually like in other editors, that Emacs had better ways of switching buffers. I ended up abandoning Tab Bar mode. But some time later, I started using it again, and I found the new version worked really well for my needs.

This post is mostly about the visual customization I use. I make the current tab blue, the other tabs gray, and the background dark gray. I use powerline to make the tabs look more like tabs:

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## Emacs: find files anywhere, updated for 2017

Back in 2016 I posted my emacs setup for finding files globally. It unifies find-file and switch-to-buffer, and also lets me find files without switching folders. I've been improving it since then and wanted to post an update.

The biggest change is speed. I profiled the code and found two bottlenecks in the construction of the global file list. The list is roughly 15000 elements, so I precomputed as much of that as I could, and the startup time went down from 0.8 seconds to 0.1 second. It feels instant now.

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## PM2.5 to Air Quality Index (AQI)

I wanted to understand the relationship between particulate matter measurements (PM2.5) and the U.S. air quality index (AQI).

The formula is on wikipedia, defined as a piecewise linear function. But it's weird that the slope isn't monotonic! It starts at 4.2, then drops to 2.1, but goes up to 2.5, then drops to 0.5, then goes up to 1.0, then back down to 0.66. Weird!

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## Building Mac OS X Emacs 26

On 11 Oct 2017 Emacs 26.0.90 pretest was released. For Mac, there's a build on emacsformacosx.com. I have been using the "Mac port" from Mitsuharu Yamamoto because it feels smoother and faster on my system, and I decided to try his development branch. Here's what I ran:

brew install gnutls texinfo libxml2
cd ~/Projects/src
git clone --branch work --depth 1 https://bitbucket.org/mituharu/emacs-mac.git
cd emacs-mac
./autogen.sh
export PATH=/usr/local/opt/texinfo/bin/:\$PATH
export PKG_CONFIG_PATH=/usr/local/opt/libxml2/lib/pkgconfig
./configure --with-mac \
--prefix=/PersonalApplications/Emacs.app/Contents/MacOS \
--enable-mac-app=/PersonalApplications
make
make install


It runs nicely!

A minor note: the byte-compiled .elc files compiled under Emacs 26 are not compatible with Emacs 25, so if you go back to an older version, you'll need to recompile the .elc files.

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