Sept 10: 1998. And this is what the artist says about his opus: I used the same algorithm and formula as Bellard, except that I wrote my program in highly optimized assembly language, which made it about 10 times faster than Bellard's program, and I publicized PiHex on the web, and asked for donations of idle computer time, so I now have (at last count) 342 computers running PiHex, in contrast to the dozen or so that Bellard used. Also, all the computers running PiHex are windows-based PCs, while Bellard used primarily unix boxes. I could write something about it, but I think that it would be of more interest to assembly-language programmers than anyone else. Colin Percival ============================================================================ He did it! Colin Percival, 17, now fully enrolled SFU student, finished his computations to find the 5-trillionth binary digit of Pi and thus established a world record for finding the largest known digit of Pi. It was the first time in history that distributed computation was used on an attempt to break the world record; previously, supercomputers had been used for this task. The algorithm for computing the nth binary digit of Pi can be nicely parallelized; Colin used a network of 25 computers, distributed all over the globe. The total running time was 4 months. (On a serial machine of comparable speed, it would have taken 17 months.) Colin is now planning to compute the 40-trillionth digit; on the same computing network, using the same algorithm, this task will take 4 years. The whole story was published in the Burnaby Newsleader last Sunday 6th; I'll get up a copy and put it in the lab shortly. Also, Colin might contribute a short note on his computations on our Web site. Jens Happe =========================================================================== From Colin_Percival@sfu.ca Thu Sep 10 14:51:14 1998 1. The actual digits: Starting at the 1.25 trillionth hexit, Pi is 07E45733CC790B5B5979. The fourth bit of this (a zero) is the five trillionth bit. 2. The dates the computation began and ended. March 21 - August 21. 3. A check was done (as in Bellard's case). Of course -- I don't trust myself enough not to check it. The calculations were done twice, 4 bits apart (like in the BBP paper), and compared. They matched perfectly apart from rounding errors. Also, before any computer was allowed to do any work, it had to pass a self-test, which consisted of calculating the one hundred millionth hexit of Pi. 4. The number of machines used. 25 computers (out of about 200 participating in PiHex) worked on the five trillionth bit. These ranged from a Pentium 60 to a dual Pentium II 333. All this information, plus the unanalyzed data (ie, partial results) are available from the PiHex web site at http://www.cecm.sfu.ca/projects/pihex/. Colin Percival