mersenneforum.org Question about Prime95 24.12 Problem???
 Register FAQ Search Today's Posts Mark Forums Read

 2005-06-23, 17:03 #1 VJS     Dec 2004 1001010112 Posts Question about Prime95 24.12 Problem??? I would like to try a very large P-1 factoring attempt. However I've been having difficulties determining the largest B1 possible. I've tried several different worktodo.ini Pminus1=24737,2,991,1,29000000000,1 However the max B1 attainable is roughtly B1=1.2G anything larger gives me an unpredictable B1 value generally much less than the input. Sorry if this has been addressed in the past.
 2005-06-23, 17:55 #2 ewmayer ∂2ω=0     Sep 2002 República de California 5×2,351 Posts Any time you start looking at p-1 bounds that large, you should first think about whether you'd be better off running ECM with appropriate bounds for whatever minimum factor size range seems likely.
 2005-06-23, 18:41 #3 VJS     Dec 2004 29910 Posts Thanks, we are currently looking at the 50 digit level for this number. Testing the required number of curves for 50 digits will take quite some time. It only seems reasonable to exhaust or at least spend at least a week or two doing a P-1 with the newer/faster/better Prime95. Looking at the record's for P-1 and P+1, a B1 bound of 10^10 don't seem too unreasonable. It can be done with ecm6.0 but prime95 is quite a bit faster. I just think it would be a shame to miss a large P-1 or P+1 factor through lack of trying while investing effort into ECM. You only have to do one P-1 at those bounds anyways then bounds less than those are also completed. Note sure if the same is true for P+1.
 2005-06-23, 19:41 #4 Prime95 P90 years forever!     Aug 2002 Yeehaw, FL 41·199 Posts Maximum B1 value is 4 billion.
 2005-06-23, 20:00 #5 VJS     Dec 2004 13×23 Posts Thank you very much, and especially thank you for the speed up with 24.12.
2005-06-23, 22:06   #6
ewmayer
2ω=0

Sep 2002
República de California

5·2,351 Posts

Quote:
 Originally Posted by Prime95 Maximum B1 value is 4 billion.
4 billion, or 2^32-1?

 2005-06-24, 16:38 #7 VJS     Dec 2004 13·23 Posts I'll let you know when it gets there. 2^32-1 - 4G = If so Looks like I get an extra 294967294 Is it possible to convert/use the P-1 stage 1 result in ecm6.0, like stage1 ecm? Is there a sticky or some brief instructions somewhere. Same goes for P+1 any "experience with posts" for the noob?
 2005-06-24, 17:57 #8 akruppa     "Nancy" Aug 2002 Alexandria 2,467 Posts Personally, I don't think P+1 is really all that useful for numbers in general. There's a 50% chance you'll merely do P-1 again and the smoothness of the group order is not as good as for ECM. If you want to factor Lucas or Fibonacci numbers, P+1 with -x0 23/11 is great and should be done instead of P-1. Alex
 2005-06-24, 18:23 #9 VJS     Dec 2004 13×23 Posts Thanks for the comments, I was just curious about other factoring techniques for 24737*2^991+1 10% of the ECM curves have been done for the 50-digit level already, and the concenses is to continue with ecm if we want to find a factor. BTW P-1 B1=2^32-1 complete starting stage2, no joy thus far.

 Similar Threads Thread Thread Starter Forum Replies Last Post Kurtbusch PrimeNet 1 2014-09-09 03:22 bertie Software 1 2012-12-16 17:56 boldenc Software 2 2009-08-09 14:33 ixfd64 Software 1 2005-09-24 08:59 GSV3MiaC Software 21 2004-01-14 14:02

All times are UTC. The time now is 03:24.

Wed Feb 1 03:24:13 UTC 2023 up 167 days, 52 mins, 0 users, load averages: 0.77, 0.82, 0.99