On 9/1/2010 9:04 PM, rcs@xmission.com wrote:
arXiv:1008.3171 (*cross-listing*) Date: Wed, 18 Aug 2010 20:17:09 GMT (53kb,D)
Title: The Two Quadrillionth Bit of Pi is 0! Distributed Computation of Pi with Apache Hadoop Authors: Tsz-Wo Sze Categories: cs.DC math.NT Comments: 9 pages, 2 figures, 3 tables MSC-class: 68Q85, 68M14, 11-04 \\ We present a new record on computing specific bits of Pi, the mathematical constant, and discuss performing such computations on Apache Hadoop clusters. The specific bits represented in hexadecimal are 0E6C1294 AED40403 F56D2D76 4026265B CA98511D 0FCFFAA1 0F4D28B1 BB5392B8. These 256 bits end at the 2,000,000,000,000,252nd bit position, which doubles the previous known record. The position of the first bit is 1,999,999,999,999,997 and the value of the two quadrillionth bit is 0. The computation is carried out by a MapReduce program called DistBbp. To effectively utilize available cluster resources without monopolizing the whole cluster, we develop an elastic computation framework that automatically schedules computation slices, each a DistBbp job, as either map-side or reduce-side computation based on changing cluster load condition. We have calculated Pi at varying bit positions and precisions, and one of the largest computations took 23 days of wall clock time and 503 years of CPU time on a 1000-node cluster. \\ ( http://arxiv.org/abs/1008.3171 , 53kb)
Memorizing two quadrillion hex digits of Pi would make a good next challenge for Daniel Tammett. Steve Gray