Wednesday, 29th January 2014

## Finding the angle around an ellipse

When is the angle around an ellipse, not the around around the an ellipse? This is a problem which tripped me up a few times when working with elliptical orbits and arcs.

### The problem

The issue is that we can (and often do) define the point on an ellipse at an angle, θ, with

x = a.cos(θ)

y = b.sin(θ)

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### Topics:

Sunday, 3rd March 2013

## Spinning globe

This post describes my highly convoluted method of making an animated globe using Khan Academy's computer science framework.

A few weeks ago I found a set of coordinates for a world map in JSON format. I can't remember where exactly, but I think it was via a StackOverflow question. The first thing I did was to convert it into an SVG world map, because I like SVG and I've been meaning to get a world map for a while.

Tuesday, 30th October 2012

## Crude matrix multiplier

[Update: A slightly more sophisticated Javascript version of my program is available to use here]

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Monday, 7th November 2011

## Python regression finder

I've been working my way through Stanford's online Machine Learning course recently and I thought I should put some of what I've learnt to use.

The program I made (file below) reads a file of tab-delimited data, assuming the first column is the independent values (x) and the second is the dependent values (y). It then gives some options:

### Topics:

Sunday, 21st August 2011

## Salman says

Analysis of subtitle text from over 1000 Khan Academy videos.

Sunday, 3rd July 2011

## Python Fibonacci generator using reduce()

Khan Academy now has a series of videos on Python programming, and I've spent way too much of this weekend watching them, despite knowing all the basics of Python (I did learn a couple of things though). In fact, I spent so much time watching video, I finally broke the million point mark (and now have 77 points in binary):

### Topics:

Saturday, 19th March 2011

## Khan Academy

A few months ago, I wrote about various places to learn online, including the Khan Academy. Then a couple of weeks ago I saw a TED talk by Salman Khan where he talked about the Khan Academy (what else?) and its recent improvements. So I went back to the website and signed up.