latest and greatest wonder of hardware overachievement is the story
of French native Fabrice Bellard, who now holds the world
record in PI calculation. He calculated Pi to 2.7 trillion
decimal digits, surpassing mark of 2.5 trillion digits set
in August by the T2K Open Supercomputer (which at the time was
the 47th most
powerful supercomputer in the world).
So what's so
impressive about Mr. Bellard's feat, aside from its basic technical
merits? He accomplished the number crunching, not on a
supercomputer, but on a Nehalem-powered desktop.
machine featured a Core i7 CPU running at 2.93 GHz, 6 GB of RAM, and
five 1.5 Terabyte Seagate Barracuda 7200.11 model hard drives (for a
total of 7.5 TB). The system ran the 64-bit Red Hat Fedora 10
distribution as its primary OS and used software RAID-0 and the ext4
The result takes up 1137 GB of storage and is
here. The computation took 103 days of computing time for
the modest desktop.
The only time when Mr. Bellard had
to enlist the help of other computers was during the verification.
In order to avoid being displaced from the top spot while the desktop
chugged on the results (that would have taken an additional 13 days),
he instead used a network of nine computers to verify the results in
a shorter timespan.
In order to calculate Pi, Mr. Bellard used
a software algorithm based on the well known Chudnovsky formula and
verified the resulting calculations by the Bailey-Borwein-Plouffe
algorithm which directly gives the n'th hexadecimal digits of Pi.
Checksums were used to detect errors.
The more optimized Pi
algorithm based on the Chudnovsky formula that Mr. Bellard uses is
the fastest current way to calculate Pi and has been renamed
Bellard's formula in his honor. Mr. Bellard is perhaps most
famous for writing the tiny c compiler (tcc), a popular lightweight
compiler in the Linux community.