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12 April 2016

Replicating Colossus's Chi-wheel setting

A worked example of one part of the cryptanalysis performed by the Colossus computer at Bletchley Park during World War II.

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23 February 2016

Bike Game in Scratch

Just over a year ago, my son (then 6) wanted to create a computer game where you drive a bike round a world. I helped him with this, and we've worked intermittently but fairly often on it since then. There were quite a few details to get right, but he worked through them a bit […]

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13 September 2015

Flying over a trampoline

Origin of idea A couple of months ago, Sally (5) was bouncing around on the trampoline at my in-laws' house, and said something very close to: 'Dad, you should take lots of pictures of me jumping in the air, and put them together into a video, then it will look like I'm flying'. I thought […]

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05 August 2015

Mono Lake alkali flies in JavaScript

We recently went on a fantastic family camping trip to California, travelling round various National and State Parks. One of the places we saw was Mono Lake. There are lots of interesting aspects to Mono Lake, but this post concentrates on one of them: the vast numbers of alkali flies which live on the waterline. […]

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26 July 2015

Guess Poo: An application of nearly-orthogonal fractional factorial design

We have the game ‘Guess Who’, which comes with a selection of sheets to play variants of the original game. In a flash of comedy inspiration, my eldest, Meg, and I thought it would be excellent if there was a game called 'Guess Poo'. In Guess Poo, instead of trying to identify faces, you have […]

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08 June 2015

Faint amusement from arrows

In logic, we talk about propositions, giving them names, say p or q. For example, p might be the proposition 'it is raining', and q the proposition 'I will get wet'. Then to represent the proposition 'if it is raining then I will get wet', we can say 'p IMPLIES q', which is often written […]

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08 April 2015

A game of multiples and divisors

I saw an interesting number-based game at the 2015 Young Scientist show. This post derives, using brute force, a winning strategy for the game and implements it as a 'human vs computer' setting.

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16 January 2015

Post-specific Javascript and CSS in WordPress

A couple of recent posts here — An oscillator from a jam-jar lid The value of a second opinion — required some post-specific Javascript and CSS styling. It took me a little while to figure out how to achieve this, given my limited exposure to PHP in general and WordPress programming in particular. This is […]

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16 December 2014

The value of a second opinion

You feel ill and go to a doctor. She does a test and says 'you have a 70% chance of having the Lurgy'. You go to a different doctor, who does a different test, but also says 'you have a 70% chance of having the Lurgy'. Given these two test results, what are your chances of having the Lurgy?

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09 November 2014

Tiny patch to git

A one-character documentation fix for 'git'.

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