Happy Pi day

March 14 is Pi Day. Yes, it is officially Pi Day. The text of the bill, passed in the House of Representatives on March 12, 2009, can be found here. Today is Pi Day because today's date, written in the form we use in the United States 3/14 where we put the month first, contains the first three digits of the number representing Pi (the Greek letter) - the ratio of a circle's circumference to its diameter. The true number? You can't write it fully because it has no known terminus. You can write it forever and people have tried to do that. It has been calculated to 2.7 trillion decimal places (as of Dec 31, 2009) but no end has yet been found. Pretty amazing to me.

There is an entertaining article on the CNN website about Pi Day. In the article, though, they mention that a number of people think that instead of praising Pi, we need to be paying tribute to Tau (another Greek letter) - the value of Pi times 2 (approximately 6.28) because so many formulas make use of that number. It is the ratio of the circle's circumference to its radius (not its diameter like Pi). If you're interested, there are a number of articles about why Tau makes a better choice for fame. One of the better ones is found here (this is an Adobe Acrobat, PDF, document).  I'll leave it to you to decide. As a certified old fogie, it's too late for me to change. But the arguments given in The Tau Manifesto (that's what the link points to) are pretty compelling.

[Full disclosure addition - I've actually posted this on March 15 (ooh - the Ides of March) but since it's about March 14, I've listed it as being posted then.]