Software engineering, systems thinking, and technical analysis.
A Formula One driver triggered my fact-checkitis. They claimed that Winning the Monaco Grand Prix in Monte Carlo is determined nine out of ten times by which position one starts in. That makes intuitive sense, because the Monte Carlo track is a narrow street t…
William Sealy Gosset was great. He improved beer at Guinness by using the statistics that existed at the time. Not happy with that, he invented new statistics to brew even better beer. The things he invented are used all over the place now, but Guinness wanted…
People assume all sorts of wild stock market returns when they make their financial calculations. Here are some numbers that show up on web searches: 6 % 8.4 % 10 % 10.1 % 11.3 % 11.5 % 13.6 % 16 % These are all correctly computed under their respective assump…
TL;DR: Instead of labouriously computing \(c = \sqrt{a^2 + b^2}\), we can mentally calculate using the alpha-max plus beta-min algorithm, by estimating \[\hat{c} = \mathrm{max}\left(a, 0.9a + 0.5b \right)\] and this will be very close to the actual \(c\). This…
In the Henley Royal Regatta two teams at a time propel their boats up a river and compete to be first to go a distance. Teams get assigned to their starting stations – Berkshire or Buckinghamshire – at random. From there, it is a straight shot up the river, wi…
Since about three years past time immemorial, the RSS feed for this site has been very anaemic. It had article titles and dates, and that was it. Many readers have requested that I include the full article in the feed, or at least a preview, but I’ve always pu…
Some decade ago I read a good implementation of fizzbuzz. What set it apart was its excellent modularity. The original article is no longer on the web, but this is my reconstruction: In[1]: module Main where import Control.Monad (guard) import Data.Foldable (f…
Some time ago I read an article on what makes a good tutor. It explicated many of the things I do when tutoring, so obviously I thought it was a great article. When I had a side gig as a private tutor, I covered mostly maths and physics, so that’s how I’ll fra…
Spaced repetition is best introduced in the words of Gwern: it is a mechanical golem that will never forget, and never let us forget whatever we chose to. If this was a medical treatment or lessons from a personal coach, it would be priced so that only high-ra…
Ada is incredibly well designed. One way this shows is that it takes the big, monolithic features of other languages and breaks them down into their constituent parts, so we can choose which portions of those features we want. The example I often reach for to…
Many of you get notified of new articles via RSS, and some of you stay tuned through the email newsletter. The email subscribers have, in the past three weeks, answered a survey on their understanding of maths topics. I asked three questions of increasing diff…
Creating abstractions should not be left to beginners. Richard Gabriel says puts it well:: Abstractions must be carefully and expertly designed, especially when reuse or compression is intended. However, because abstractions are designed in a particular contex…
The internet is full of people dismissing lines of code as a measurement. People say things like Lines of code written has been firmly established over the decades as a largely meaningless metric. and (Continue reading the full article on the web.)
When interacting with databases in Haskell, we use a library called Persistent to create mappings between database content and Haskell data types. This library can also query for records and update them, as long as the operations involved are very basic. Once…
I was reading the METR article on how LLM code passes test much more often than it is of mergeable quality. They look at the performance of LLMs doing programming when the success criterion is “passes all tests” and compare it to when the success criterion is…
I read Ian Whitlock’s article on why he can’t quit Magit and it inspired me to share more about Magit from my perspective. This article will focus on rebasing. Here I have opened the git log, by first opening Magit (which I have bound to the F3 key), and then…
Teaching an adult to ride a bike is easy. This is how: You hand them a smaller bike so they can comfortably reach the ground. You instruct them to not focus on going in any particular direction, but instead always steer into the fall. (Continue reading the ful…
TL;DR: To use a shell script as a Nix flake check, turn it into a derivation with runCommand. It must Create a file named as suggested in the environment variable $out. Print the desired “how to fix” information to stdout. Exit with status code 1 if the check…
The problem with Qwerty keyboards on small touchscreen devices is that they are designed for ten-finger typing, and we typically only use two thumbs to type. Surely there must be ways input can be optimised for two thumbs beyond the Qwerty keyboard. Obviously,…
Imagine we want to figure out what round-trip times we can expect between Sweden and New Zealand. We ping a server belonging to the University of Waikato from Stockholm, and record the following round-trip times in milliseconds. 290 388 299 290 462 292 291 293…
Rajiv Prabhakar presents us with a hypothetical: You and your friend are walking by a magic store and find a trick coin. You toss it 14 times and end up with 10 heads. Your friend thinks at least one of the next two tosses will end up tails, and is willing to…
Here’s an example of a system of equations I came across. \[\left\{\begin{array}{l} & 4x & - & 3y & = & -17 \\ - & 2x & + & y & = & 7 \end{array} \right.\] There’s a fast way to solve this, which is to take two of the lower equation and add to the upper equati…
The 2026 ACX prediction contest asks whether any justice of the Supreme Court (SCOTUS) will leave during the year. Well, actually it asks whether one of two things will happen: Congress enacts a bill that changes the number of seats in the SCOTUS; or a sitting…
One of the questions of the 2026 ACX prediction contest is whether Nvidia’s stock price will close below $100 on any day in 2026. At the time of writing, it trades at $184 and a bit, so going down to $100 would be a near halving of the stock value of the highe…
The last few questions of the ACX 2025 prediction contest just resolved. This means we can take stock of what went right and what went wrong. My preferred metric of forecasting performance is the average blind Brier score, since this is what’s popularly used a…
Kitchen work is all about proportions: sometimes the recipe is for four servings but you need six; maybe the recipe calls for 80 g of butter but you only have 57 g, so you have to adjust the other ingredients to match. We could use an electronic calculator to…
Here are the costliest natural disasters per year, since 1900. This covers only single events; it does not count longer-running processes like multi-year droughts. (Continue reading the full article on the web.)
I evaluate LLMs by how well they play text adventures. The last update I made was when Haiku 4.5 was released. Now that Google has released a preview of Gemini 3 Flash, I had to run the benchmark again. I had expected it to blow the other models out of the wat…
As readers of the premium newsletter know, I have been playing some more go recently. In particular, thanks to the release of the book Mastering Mini Go, I have discovered how exciting go on a 9×9 board is. I feel like this faster-paced, smaller game has taugh…
The MIL-STD-882E standard specifies levels of software control, i.e. how dangerous the software can be based on what it is responsible for. Although the standard is a little more complicated, we can simplify to essentially four levels: The most alarming case i…