It’s one of the most mysterious numbers in mathematics, and clearly one of the most loved. Well, how else did the little pi manage to wrangle two celebratory days a year – Global Pi Day, March 14, to represent pi’s decimal value of 3.14 and coincidentally Albert Einstein’s birthday; and Pi Approximation Day, July 22, to represent its fractional avatar 22/7.

Even as you read this, T-shirts, mugs and other memorabilia are being sold in various parts of the world to celebrate the world of pi ( ). In mathematics, pi denotes the ratio of the circumference of a circle to its diameter and was first given its 22/7 formulation by Archimedes.

In India, there may not be memorabilia but the day is being marked with lectures and seminars on the mystery of pi as well as its Indian connection. “As this is also the Year of Mathematics in India, being Srinivasa Ramanujam’s 125th birth anniversary, mathematicians have been giving a series of lectures over the weekends in different parts of Chennai,” says R Sivaraman, of the Pie Mathematics Association, who will be speaking on Ramanujam’s life and contributions next week.

“Ramanujam provided great insight into the computation of pi through his power series formulae,” says Sivaraman. “Thanks to his formulae, for the first time, the pi value could be accurately calculated up to 17.5 million digits. No one had managed that before,” says Sivaraman. Now, of course, thanks to Ramanujam’s formulae, computers can calculate the pi decimal value up to 1.24 trillion digits. “Pi is central to every mathematician’s research. You just cannot steer clear of it,” says  Professor Rajeeva L Karandikar,  director, Chennai Mathematical Institute.

“You need pi for everything, right from digging a well to sending satellites into space,” says Sivaraman, who adds he believes that the more you know of pi, the more secrets of nature you can unlock. Incidentally, ancient Indian mathematicians Aryabhatta and Bhramagupta also cut into pi. Astronomer-mathematician Aryabhatta of the sixth century AD calculated its value up to four places, while Bhramagupta in the eighth century AD, used 3 as a “practical” value of pi, and the square root of 10 as an “accurate” value of pi.

source: http://www.timesofindia.indiatimes.com / Home> City> Chennai / by Kamini Mathai, TNN / July 22nd, 2012