20050623, 17:03  #1 
Dec 2004
100101011_{2} Posts 
Question about Prime95 24.12 Problem???
I would like to try a very large P1 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. 
20050623, 17:55  #2 
∂^{2}ω=0
Sep 2002
República de California
5×2,351 Posts 
Any time you start looking at p1 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.

20050623, 18:41  #3 
Dec 2004
299_{10} 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 P1 with the newer/faster/better Prime95. Looking at the record's for P1 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 P1 or P+1 factor through lack of trying while investing effort into ECM. You only have to do one P1 at those bounds anyways then bounds less than those are also completed. Note sure if the same is true for P+1. 
20050623, 19:41  #4 
P90 years forever!
Aug 2002
Yeehaw, FL
41·199 Posts 
Maximum B1 value is 4 billion.

20050623, 20:00  #5 
Dec 2004
13×23 Posts 
Thank you very much, and especially thank you for the speed up with 24.12.

20050623, 22:06  #6  
∂^{2}ω=0
Sep 2002
República de California
5·2,351 Posts 
Quote:


20050624, 16:38  #7 
Dec 2004
13·23 Posts 
I'll let you know when it gets there.
2^321  4G = If so Looks like I get an extra 294967294 Is it possible to convert/use the P1 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? 
20050624, 17:57  #8 
"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 P1 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 P1.
Alex 
20050624, 18:23  #9 
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 50digit level already, and the concenses is to continue with ecm if we want to find a factor. BTW P1 B1=2^321 complete starting stage2, no joy thus far. 
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