# Pi Day 2014

For several years now, on March 14th, members of the SFU IRMACS Centre have observed Pi Day. Pi Day is a world wide annual celebration commemorating the mathematical constant π (pi).

One of the reasons why the IRMACS Centre celebrates Pi Day is that Dr. Peter Borwein, the Founding Director of the IRMACS Centre, has had a long standing interest in the number Pi. Here are a few details that illustrate how Dr. Borwein's work is linked with the most famous of all numbers. Dr. Borwein, his brother Jonathan, and Dr. David Bailey of NASA co-wrote the 1989 paper demonstrating how to compute one billion digits of pi. This paper was awarded the 1993 Chauvenet and Hasse prizes for expository writing. In 1995, the Borweins and Dr. Yasumasa Kanada of the University of Tokyo, took pi to over four billion digits. That same year, working with Dr. Bailey and Dr. Simon Plouffe, now at the University of Quebec, Dr. Borwein developed an algorithm known as the BBP (Bailey-Borwein-Plouffe) formula to calculate the individual hexadecimal digits of pi. In other words, they were able to arrive at the *n*th digit of pi without calculating all the preceding digits. (By the way, the quadrillionth binary digit of pi is 0.) In 1999, Dr. Borwein co-authored the book "Pi: A Source Book".

The current record as of December 28, 2013 is 12 trillion decimal digits calculated by Alexander J. Yee and Shigeru Kondo. Yee and Kondo mention Dr. Borwein's work in the following way: "To verify correctness of the hexadecimal digits [in our calculations], the BBP formula was used to directly compute hexadecimal digits at various places (including the 4,152,410,118,610th place)."

Why compute the digits of Pi? In Dr. Borwein's words: "Sometimes it is necessary to do so, though hardly ever more than six or so digits are ever really needed. Whatever the personal motivations, π has been much computed and a surprising amount has been learnt along the way. The computation of Pi seems to stretch the machine and there is a history of uncovering subtle and sometimes not so subtle bugs at this stage."

This year's Pi Day celebration will take place in the IRMACS Presentation Studio, ASB 10900, on Friday, March 14, starting at 11:30. Dr. Veselin Jungic of the SFU Department of Mathematics and The IRMACS Centre will give a presentation titled "Pi Day Trivia: An Experiment."

As part of the IRMACS Centre's traditional Pi Day celebration the audience will be asked to participate in an activity that has never been tried before, at least not in the IRMACS Centre's Presentation Studio! Please bring your laptop or some other wireless device to participate. Regardless of the success of our experiment everybody will get to enjoy a piece of pie at the end." Dr. Jungic's talk is intended for a general audience.

Pie a la mode will be served for those that attend the talk.

Everyone is welcome!

Contact: Veselin Jungic vjungic@irmacs.sfu.ca

The image above is from the animated movie Math Girl 3 “Rationalize This” by Lou Crocket and Veselin Jungic.