## Carnival of Math #76

Welcome to the very late 76th carnival of Maths. As per tradition, lets start with the trivia. 76 is an automorphic number , can be written as a sum of three squares (2^2+6^2+6^2) and is the 9th Lucas number.

Every now and then I get asked the question ‘Eigenvectors….so what are they good for?’ I’ve got a few stock answers but Language Log’s Mark Liberman goes the extra mile when he considers how they might have been used in Cinderella and goes on to discuss how they are used in linguistics. Are you suitably intrigued? Check it out in Eigenfeet, eigenfaces, eigenlinguistics, …

If you have worked on the classification of multivariate data then you may well have heard of or used the Mahalanobis distance (I came across it for the first time when working with MATLAB’s pdist function). It turns out that this commonly used metric has rather surprising origins! Read all about it in Anthropometry and Anglo-Indians over at Jost a Mon.

March 14th is, of course, Pi day and several bloggers have written something about everyone’s favouburite irrational number. Carnival regular, John D. Cook, brings us A Ramanujan series for calculating pi, 360 has The Difference and Qiaochu Yuan counters with Pi is still wrong. Finally, madkane brings us a Pi day limerick.

Over at God Plays Dice, Michael Lugo brings us A street-fighting approach to the variance of a hypergeometric random variable and some of Denise’s favourite math websites have gone AWOL over at Let’s Play Math. Can you help her find them?

Peter Rowlett asked Twitter for links to enthuse people about mathematics. Here are the answers. Finally, Guillermo Bautista gives us an example of the epsilon-delta definition of limits.

**Your Carnival needs you**

The Carnival of Math desperately needs people to write and host future editions. If you have a math related blog and would like a bucket-load of extra traffic then contact me for more information.

Pi day: Its the 14’th of march!

March 24th?! I think I need to update a few calculations… ;)

Just testing guys, just testing :)

Fixed now!

Cheers,

Mike

Glad to see the carnival — better late than never! Now I’m off to enjoy browsing…

Thanks for including my article Mike.