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Old 2005-01-18, 11:32   #1
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Default Stage 2 P-1 already done or never done?

last night my computer finished stage 1 p-1 factoring and did some sort of stage 1 GCD then went right on to L-L testing, my question is, was the stage 2 p-1 factoring already done on the exponent by another person before I got it to L-L test, and if so, why weren't any of the other factoring tests done?
hope someone can clear this up,
Mr. 0.45% L-Ling of second exponent
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Old 2005-01-18, 12:03   #2
marc
 
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If you don't have enough memory allocated to prime95/mprime then it'll skip Stage 2. Trial factoring will likely have already been done much earlier by someone else.

Last fiddled with by marc on 2005-01-18 at 12:04
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Old 2005-01-18, 12:34   #3
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that's probably it, I had 8 MB (I think that's the default) allowed for Prime95, and I did the trial factoring on it myself before the Stage 1 P-1 factoring
so the Stage 2 on that exponent will never be done? just kinda answered that myself, if the L-L shows up not prime then it won't need to be done
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Old 2005-01-18, 23:40   #4
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Mr. >0.45% L-Ling of second exponent,

Eventually someone will come along to use P-1 stages 1 & 2 with large bounds on your exponent in a follow-on effort to try to find a factor (this is a separate project from your searching for Mersenne primes), but don't worry about it. When your computer did the P-1, your copy of Prime95 chose the optimum bounds for maximizing its usefulness to GIMPS, taking into account your computer's CPU type, speed, and memory allocation.

If you'd allocated more memory, Prime95 might have done stage 2 to look somewhat deeper for a factor, but the small advantage in factor-finding efficiency is definitely not big enough to justify redoing, or worrying about, it!
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Old 2005-01-19, 17:37   #5
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ok, I'm glad that thing is cleared up about that
p.s. it will be a while till they find a factor for mine, huh? since they just found 971 exponent's factor according to www.mersenne.org
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Old 2005-01-19, 21:02   #6
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Quote:
Originally Posted by Unregistered
ok, I'm glad that thing is cleared up about that
p.s. it will be a while till they find a factor for mine, huh? since they just found 971 exponent's factor according to www.mersenne.org
It could be that they never find a factor. Although there are benefitsin looking for a factor, they might be completely overwhelmed by thecosts associated with looking for one. Therefore, unless there's someserious benefit in looking for a factor later in the future, I couldeasily imagine that they'll never even try.
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