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-   -   P-1 factoring anyone? (https://www.mersenneforum.org/showthread.php?t=11101)

kladner 2012-01-31 15:40

[QUOTE=bcp19;287886]Sorry, I hadn't ruled that out, it just seemed an awful big jump in bounds for just a few extra levels.[/QUOTE]

On the bright side, you caused some very informative discussion to take place, clearing up some misconceptions.:smile:

Dubslow 2012-01-31 17:57

[QUOTE=bcp19;287886]Sorry, I hadn't ruled that out, it just seemed an awful big jump in bounds for just a few extra levels.[/QUOTE]

Consider that the total number of candidates tested for the higher one was 8x greater than the other four. From that view, it's no wonder the P-1 bounds dropped.

Mini-Geek 2012-02-01 03:38

[QUOTE=Prime95;287885]The biggest source of deviation from 1000 is that prime95's initial estimate is not very accurate.[/QUOTE]

On a four core machine, is it expected to be around 1000 or around 4000? Mine is currently at 3707 (it was lingering around 2000 when I manually bumped it up to ~4000, as I mentioned), which is roughly accurate. The CPU is an i5-750@2.8GHz. If you want more info (e.g. for debugging, to make the estimate more accurate) let me know.

cheesehead 2012-02-01 09:36

[QUOTE=bcp19;287886]Sorry, I hadn't ruled that out, it just seemed an awful big jump in bounds for just a few extra levels.[/QUOTE]Mr. Dickman's function ( [URL]http://en.wikipedia.org/wiki/Dickman_function[/URL] , [URL]http://mathworld.wolfram.com/DickmanFunction.html[/URL] ) leads to some broad maxima in the optimization function.

Mr. P-1 2012-02-02 12:00

[QUOTE=lorgix;287746](For that particular assignment you may want to adjust the memory settings so that 40 or 48 relative primes can be processed at once.)[/QUOTE]

44 relative primes is just fine, finishing stage 2 in eleven passes. 40 would need twelve passes, while 48 would do it in ten. The difference in performance would be miniscule.

cheesehead 2012-02-02 18:26

"Miniscule" (or, at least, "Detail Oriented") is some of our middle names around here.

LaurV 2012-02-03 03:06

[URL="http://www.youtube.com/watch?feature=endscreen&NR=1&v=Zy77SXP-nxY"]Miniscule[/URL]... that is like factoring, hard and odd.. :D

bcp19 2012-02-03 07:30

I was looking for some easy numbers to get a better understanding of the P-1 process, and in looking at M2011, it lists bounds of 5 and 27 where K=2*2*3*3*3*5. As I was working through this, I got to thinking, couldn't this also be found with bounds of 5 and 9? In using 27, you'd have 2*2*5 from S1 and 27 from S2, but wouldn't 2*2*3*5 from S1 and 9 from S2 also work?

axn 2012-02-03 08:35

[QUOTE=bcp19;288146]I was looking for some easy numbers to get a better understanding of the P-1 process, and in looking at M2011, it lists bounds of 5 and 27 where K=2*2*3*3*3*5. As I was working through this, I got to thinking, couldn't this also be found with bounds of 5 and 9? In using 27, you'd have 2*2*5 from S1 and 27 from S2, but wouldn't 2*2*3*5 from S1 and 9 from S2 also work?[/QUOTE]

Where did you get this information? Neither 5,27 nor 5,9 will find this. A stage 1 bound of 27 is needed to find this.

With B1=27, you'd use an exponent of 2^4*3^3*5^2*7*11*13*17*19*23, which'd find the factor.

MrHappy 2012-02-03 10:24

1 Attachment(s)
29.8 percent chance of finding a factor!? Is that expectation correct? Until today I have only seen values from 4 to 7 percent...

axn 2012-02-03 10:31

[QUOTE=MrHappy;288162]29.8 percent chance of finding a factor!? Is that expectation correct? Until today I have only seen values from 4 to 7 percent...[/QUOTE]
>>>>> Assuming no factors below 2^-1 <<<<<

There is nothing wrong here. Nothing at all... :whistle:


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