Brian, >>We will of course have to check factors considerably further than we are >>doing on our current exponent range (due to the increased LL iteration time.) > Yes - on the principle that it's worthwhile to spend 5% to 10% of the > LL testing time attemptimg to find at least one factor before we run > a LL test, the pre-factoring should be run for 3 or 4 weeks per > exponent first (assuming PIII-500 class power). At a rough guess, > that's up to 2^66 or 2^67, but we don't have any benchmarks yet. Sounds about right for a SWAG estimate. > Of course, trial factoring to 2^40 is very quick - I spent only about > 2 (PII-350) CPU hours spread over all 159,975 candidate exponents in > the range I selected. But that's enough to eliminate a third of them. Maybe we should start checking factors in (the range of prime numbers used in your database) in 2^40 segments, between you and me (and others?). > If anyone's _really_ keen I could send them the source of the program > I used (needs MS VC++). It's reasonably efficient & will go to 2^63. > Exponents in the 30 millions are not acceptable to Prime95 v18 and > its derivatives. Just call me "Mr. Keen." ;) When you send me the source, I'll try to port it GCC (then maybe we can make something useful out of it :-) A few questions: What type of sieving did you do (if any) ? Did you write the modpow routine, or was it included with some math header? How much room for improvment in speed would you say is there in the source? I have limited computational resources, a PII233, a P100, but because of my work, I have practically unlimited resources in the 486 department they could finish a 2^40 section in about a day or so. I hope this 10,000,000 digit thing will go somewhere. It would be keen to have this range checked in maybe 2 years, attracting many new members to GIMPS in the process. -Lucas Wiman ________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
