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Mark Nelson

Dr. Dobb's Bloggers

5 Trillion Digits of Pi

August 06, 2010

Back in 1981, fresh out of school, I was awestruck by Steve Wozniak's program that calculated over 100,000 digits of e on an Apple II. Shortly after reading the article, I ported his program to the PDP-11 at my office and duplicated his results, down to the last digit.

These days the stakes are much higher when it comes to calculating the values of constants. Alexander Yee and Shigeru Kondo have just announced the calculation of pi to 5 trillion digits. And oddly enough, this was accomplished on a desktop machine running Windows server, not the Linux cluster I would have expected.

Here are some of key stats:

Operating System
Windows Server 2008 R2 Enterprise x64


2 Intel Xeon X5680 @3.33 GHz offering 24 hyperthreaded processors

Disk Space
The computation required roughly 22TB of disk space, and the compressed result takes another 3.8TB

The task took 90 days to complete, and 66 hours to verify

The y-cruncher software package that broke this record also holds records for several other constants, including one trillion digits of e. So in 30 years, more or less, the desktop PC has gone from constant calculations under a million digits to over a trillion digits. That growth rate of 1.7x per year maps pretty well to Moore's Law, suggesting that we can expect these numbers to continue climbing for at least a few more years.

Kudos to Alexander Yee and Shigeru Kondo on a smashing accomplishment!

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