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A billion digits of pi.

A billion digits of pi

When it comes to computing the decimal digits of pi (the ratio of a circle's circumference to its diameter), a records are made to be broken. With an infinite number of digits to pursue, enthusiasts keep trying to extend the number of digits known, though they have no hope of ever reaching the end.

Now, just a few months after calculating 480 million digits (SN: 6/17/89, p.372), mathematicians Gregory V. and David V. Chudnovsky of Columbia University in New York City have broken the billion-digit barrier, using their innovative techniques to compute the verify 1,011,196,691 digits in the chemical expansion of pi.

The Chudnovskys ran their programs on an IBM-3090 computer, using two different operating systems. Printed out in a line, the digits they computed would stretch nearly halfway across the United States. The first computer calculation of pi in 1949 reached only 2,037 digits.

The Chudnovskys intend to give up their pursuit of pi, at least for now. "If somebody comes along and wants to use our algorithm, that's fine," David Chudnovsky says. "But we are out of the game."

Still in the game is computer scientist Yasumasa Kanada of the University of Tokyo, who previously held records for computing the digits of pi (SN: 4/2/88, p.215). In July, Kanada used a modified version of his pi-computing program on a Hitachi supercomputer to reach 536,870,000 digits. To spend up his program further, Kanada is investigating ways of hastening the multiplication of numbers up to a billion digits long. "I hope to continue, but it all depends on the availability of new machines," Kanada told SCIENCE NEWS. In his effort to break the present record, he's hoping to get time on any one of several new supercomputers now being developed in Japan.
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Title Annotation:computing the decimal digits of the ratio of a circle's circumference to its diameter
Author:Peterson, Ivars
Publication:Science News
Date:Sep 9, 1989
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