Monthly Archives: October 2010

Pi seconds equals one nanocentury

Duff’s rule says that a nanocentury is about π seconds. Assuming a year is 365.25 days, there are 3,155,760,000 seconds in a century. So a nanocentury, one billionth of a century, is 3.15576 seconds, roughly π seconds. This odd fact

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There isn’t a googol of anything

Before Google, there was googol, the number 10^100, written as a 1 followed by 100 zeroes. There are about 4 × 10^79 atoms in the universe. (Here’s a derivation of that number.) You could bump that number up a little

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Posted in Math

Ten music posts

Ten previous blog posts on music. Odd meters Music in 5/4 time Blue Rondo à la Turk March in 7/4 time Music and computers Typesetting music in LaTeX with LilyPond Windows XP and Ubuntu start-up music Music and math Opening

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Posted in Music

Emacs calculator

Emacs has quite a sophisticated scientific calculator. Like many other things in Emacs, it is both powerful and idiosyncratic.

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Posted in Computing

Math Fun Facts for iPhone

Math Fun Facts is a large collection of very short mathematical articles, each less than a page, maintained by my friend Francis Su. These articles are a great resource for teachers looking for interesting examples to spice up a class.

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Posted in Math

Weekend miscellany

Google Google street view Antarctica Google’s alternative to JPEG Statistics Three-quarter truths: correlation is not causation Bounds for non-central chi-square tails Miscellaneous Math lessons for locavores Victorian submarines How ink is made

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Probability that a number is prime

The fastest ways to test whether a number is prime have some small probability of being wrong. Said another way, it’s easier to tell whether a number is “probably” prime than to tell with certainty that it’s prime. This post

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Posted in Math, Statistics

Casablanca and Einstein

If you’ve ever seen Casablanca, you’ve heard the song As Time Goes By, but only the chorus. You must remember this A kiss is just a kiss, a sigh is just a sigh. The fundamental things apply As time goes

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Posted in Math

Probability and Statistics cheat sheet

Matthias Vallentin posted a comment on my post about a math/CS cheat sheet to say that he’s been working on a probability and statistics cheat sheet. Looks great, though at 24 pages it stretches the definition of “cheat sheet” even

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Posted in Math, Statistics

Serious lessons from Knuth’s joke

On June 30, 2010 Donald Knuth announced iTeX, the successor to TeX. His announcement was an extended parody of much of what people recommend as the “right” way to develop software. TeX has been extremely successful. The vast majority of

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Posted in Software development

Math/CS cheat sheet

Here’s something called a theoretical computer science cheat sheet. I don’t know whether I agree with the name, but it’s a nice cheat sheet. The first two pages of the cheat sheet have to do with sums, combinatorics, and recurrence

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Posted in Math

Weekend miscellany

Music Classical sacred music Music in 5/4 time Math The history and future of special functions Carnival of Mathematics blog Computing Running Facebook’s servers How to write a Lisp interpreter in Python Productivity The myth of laser focus Podcast on

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