Author: John

All possible scales

Pete White contacted me in response to a blog post I wrote enumerating musical scales. He has written a book on the subject, with audio, that he is giving away. He asked if I would host the content, and I am hosting it here. Here are a couple screen shots from the book to give […]

Ellipsoid distance on Earth

To first approximation, Earth is a sphere. But it bulges at the equator, and to second approximation, Earth is an oblate spheroid. Earth is not exactly an oblate spheroid either, but the error in the oblate spheroid model is about 100x smaller than the error in the spherical model. Finding the distance between two points […]

Sequence alignment

In my previous post I illustrated the Levenshtein edit distance by comparing the opening paragraphs of Finnegans Wake by James Joyce and a parody by Adam Roberts. In this post I’ll show how to align two sequences using the sequence alignment algorithms of Needleman-Wunsch and Hirschberg. These algorithms can be used to compare any sequences, though they […]