Monthly Archives: September 2009

Circle of fifths and roots of two

A chromatic scale in Western music divides an octave into 12 parts. There are slightly different ways of partitioning the octave into 12 parts, and the various approaches have long and subtle histories. This post will look at the root

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Posted in Music

Achievement is not normal

Angela Duckworth gave a 90-second talk entitled Why Achievement Isn’t Normal. She’s using the term “normal” in the sense of the normal (Gaussian) distribution, the bell curve. With normally distributed attributes, such as height, most people are near the middle

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Posted in Statistics

JavaScript: A picture is worth a thousand words

Here’s a photo posted by David Walsh on Twitter on yesterday. Related links: Programming language subsets I wish someone would write “R, The Good Parts” Programming language fatigue JavaScript: The Definitive Guide JavaScript: The Good Parts

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Posted in Software development

Weekend miscellany

The truth about operating systems Who has babies when? Socio-economic factors influence birth months Clinical trial of traditional Chinese medicine made from toad venom for treating cancer A summer intern’s perspective on Enron Joel Spolsky’s Duct Tape Programmer post and

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How many trig functions are there?

How many basic trigonometric functions are there? I will present the arguments for 1, 3, 6, and at least 12. The calculator answer: 3 A typical calculator has three trig functions if it has any: sine, cosine, and tangent. The

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Posted in Math

Poverty versus squalor

In his interview on EconTalk, Paul Graham made a distinction between poverty and squalor. He says that most poor people live like rich people, but with cheap imitations. A rich person might have something made of gold and a poor

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Posted in Business, Creativity

Feed the stars, milk the cows, and shoot the dogs

The blog Confessions of a Community College Dean had a post on Monday entitled Cash Cows that talks candidly about the financial operations of a community college. It’s a commonplace of for-profit management that units can be characterized in one

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Posted in Business

Software profitability in the middle

Kent Beck made an interesting observation about the limits of open source software on FLOSS Weekly around one hour into the show. These aren’t his exact words, just my summary. Big companies like IBM will contribute to big open source

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Posted in Business, Software development

Three views of the negative binomial distribution

The negative binomial distribution is interesting because it illustrates a common progression of statistical thinking. My aim here is to tell a story, not to give details; the details are available here. The following gives a progression of three perspectives.

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Posted in Statistics

Free alternative to Consolas font

Consolas is my favorite monospace font. It’s a good programmer’s font because it exaggerates the differences between some characters that may easily be confused. It ships with Visual Studio and with many other Microsoft products. See this post for examples.

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Posted in Typography

Inverse Mercator projection

In my earlier post on the Mercator projection, I derived the function h(φ) that maps latitude on the Earth to vertical height on a map. The inverse of this function turns out to hold a few surprises. The height y

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Posted in Math

Weekend miscellany

If you’re new to this blog, thank you for coming by. Please see my note to new subscribers. There is also a podcast version of the blog. J. S. Bach’s Crab Canon. Hear what happens when you twist the sheet

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Make up your own rules of probability

Keith Baggerly and Kevin Coombes just wrote a paper about the analysis errors they commonly see in bioinformatics articles. From the abstract: One theme that emerges is that the most common errors are simple (e.g. row or column offsets); conversely,

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Posted in Science, Statistics

Conservation of complexity

Larry Wall said something one time to the effect that Scheme is beautiful and every Scheme program is ugly; Perl is ugly, but it lets you write beautiful programs. Of course it also lets you write ugly programs if you

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Posted in Software development

Mercator projection

A natural approach to mapping the Earth is to imagine a cylinder wrapped around the equator. Points on the Earth are mapped to points on the cylinder. Then split the cylinder so that it lies flat. There are several ways

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Posted in Math