20030724, 21:37  #1 
Jul 2003
6_{8} Posts 
chance of finding a factor?......Read me read me read me :)
when you 1st start the LL test prime95 says
"chance of finding a factor is an estimated X.XX%" what do most people get for the X.XX% 
20030725, 08:08  #2 
Jul 2003
2·3 Posts 
50 people read this and no one posts a single thing...:(

20030725, 08:14  #3  
"Sander"
Oct 2002
52.345322,5.52471
10010100101_{2} Posts 
Re: chance of finding a factor?......Read me read me read me
Quote:


20030725, 08:37  #4 
Jul 2003
2×3 Posts 
ummmm...yeah that also.....LOL
my bad so when testing a number what are the steps? factoring 2^x P1 factoring then what? 
20030725, 11:17  #5 
Dec 2002
Frederick County, MD
2·5·37 Posts 
After the program finishes trial factoring (factoring 2^x) and p1 factoring, if a factor is not found, it will perform the LucasLehmer (LL) test. The idea for factoring is that maybe we can find a small factor of the number to show that the number is not prime, so we don't have to perform the LL test, because the LL test can take from several weeks to several months, depending on the computer and depending on the exponent.
And if the LL test starts, it has to get all the way to 100% to determine if the number is prime or not. The LL test doesn't find factors, it just determines primality. 
20030725, 12:03  #6 
"Mark"
Feb 2003
Sydney
3×191 Posts 
The last P1 test I saw start gave a probability something like 4.87%. It will vary with how much memory you allow prime95 to have (and probably other stuff).

20030725, 12:35  #7 
Jul 2003
UK
3×17 Posts 
Just started doublechecking a 9M exponent
P1 bounds B1=50000 B2=750000 Chance of finding a factor is an estimated 2.91% 
20030725, 13:43  #8 
Oct 2002
Lost in the hills of Iowa
2^{6}·7 Posts 
I think I usually get an estimate around 4.5%, but I'm NOT gonna stop and restart clients just to check  and I don't think Prime gives that estimate anyway at anytime other than the start of the P1 1'st stage?

20030725, 14:41  #9 
Aug 2002
2^{3}×5^{2} Posts 
3.62% for M10979453 with bounds B1=60000, B2=1020000

20030725, 17:10  #10 
Jul 2003
2×3×5 Posts 
M10983677 B1=60000 B2=1110000 (64 bit level) 3.38%
M10983677 B1=55000 B2=907500 (65 bit level) 2.8% M10983677 B1=50000 B2=775000 (66 bit level) 2.31% Prime set to use 400MB of ram on all cases. So as you can see it all depends on how far that factor has been factored up to this point. The higher you go the less likely you are to find a factor, which makes sense. 
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