mersenneforum.org > Data Mersenne.ca Status Report
 Register FAQ Search Today's Posts Mark Forums Read

2017-12-10, 09:24   #166
tha

Dec 2002

827 Posts

Quote:
 Originally Posted by axn The math is fine. I'll have to look at source to see if the code deviates from the math. It is also possible that stage 2 inadvertently picked up one 821 (especially here, since B-S degree 12 was used), but we can't reliably use it to back calculate B1/B2. A correctly implemented P1, to reliably recover this factor every time, must use B1=821^2.
from results.txt:

Code:
[Sat Dec 09 16:46:59 2017]
P-1 found a factor in stage #2, B1=350000, B2=7000000, E=12.
UID: ANONYMOUS, M22411801 has a factor: 1043187363347975865450924439 (P-1, B1=350000, B2=7000000, E=12)
The fact that it was found in stage 2 and not in stage 1 might be telling.

My guess is that the mprime/prime95 stage 2 code can do power of 2 of exponents up to the square root of B2 by cleverly picking up not only all values between square root of B1 and square root of B2 but from 2 all the way up to the square root of B2. We would need to check the mprime/prime95 code.

Last fiddled with by tha on 2017-12-10 at 09:39

2017-12-10, 10:21   #167
axn

Jun 2003

23×643 Posts

Quote:
 Originally Posted by tha My guess is that the mprime/prime95 stage 2 code can do power of 2 of exponents up to the square root of B2 by cleverly picking up not only all values between square root of B1 and square root of B2 but from 2 all the way up to the square root of B2. We would need to check the mprime/prime95 code.
Checked the code. It only looks for prime products <= B1. So the explanation is stage 2 B-S extension. Note that stage 2 only needed to account for the 821. Everything else is accounted for by stage 1. With E=12, this could probably happen in any number of ways.

 2018-06-17, 20:53 #168 James Heinrich     "James Heinrich" May 2004 ex-Northern Ontario 22·53·7 Posts Yes, if anyone's looking right now, mersenne.ca is down for maintenance, should be back up within a few minutes (or many minutes, depending on how quickly the database updates process). edit: it should be back up. Let me know if you see anything weird since I did adjust some database table structures. Last fiddled with by James Heinrich on 2018-06-17 at 22:19
2018-06-17, 22:48   #169
storm5510
Random Account

Aug 2009

22·32·5·11 Posts

Quote:
 Originally Posted by James Heinrich Yes, if anyone's looking right now, mersenne.ca is down for maintenance, should be back up within a few minutes (or many minutes, depending on how quickly the database updates process). edit: it should be back up. Let me know if you see anything weird since I did adjust some database table structures.

Everything looks good on my end.

 Similar Threads Thread Thread Starter Forum Replies Last Post Gordon mersenne.ca 21 2019-01-21 02:38 Dubslow PrimeNet 2 2015-10-05 05:21 Gordon mersenne.ca 1 2015-09-22 10:53 rogue Sierpinski/Riesel Base 5 8 2006-03-04 13:59 PrimeCruncher PrimeNet 11 2005-10-09 18:53

All times are UTC. The time now is 06:53.

Sun Oct 17 06:53:10 UTC 2021 up 86 days, 1:22, 0 users, load averages: 1.56, 1.19, 1.02