mersenneforum.org  

Go Back   mersenneforum.org > Great Internet Mersenne Prime Search > Data

Reply
 
Thread Tools
Old 2004-11-26, 19:16   #1
jocelynl
 
Sep 2002

2·131 Posts
Default Useless p-1 work

Quote:
77900201,825000,22893750
77900461,825000,22893750
77900497,825000,22893750
77909939,825000,22893750
79279351,825000,15881250
79299397,780000,11700000
79299421,725000,7612500
79299433,660000,3465000
79299719,780000,12480000
79299821,1110000,1110000
79299907,1110000,1110000
79299959,740000,16465000
What a waste of cpu cycles!
all b1's are smaller than m so they assume that the largest factor of p-1 is m and they don't reach it.

what a waste!

Joss
jocelynl is offline   Reply With Quote
Old 2004-11-26, 20:55   #2
xilman
Bamboozled!
 
xilman's Avatar
 
May 2003
Down not across

32·1,129 Posts
Default

Quote:
Originally Posted by jocelynl
What a waste of cpu cycles!
all b1's are smaller than m so they assume that the largest factor of p-1 is m and they don't reach it.

what a waste!

Joss
Be careful! George's code includes an additional m over and above the ones implied by the b1 limit. I asked him this very question some time ago.

Paul
xilman is online now   Reply With Quote
Old 2004-11-26, 21:21   #3
jocelynl
 
Sep 2002

4068 Posts
Default

So I see!

I tested 2^251-1
b1=2 b2=2 and found the factor 27271151

Tks xilman
You're right, b1 is actually b1+m
There was no wasted cycle.
I pushed the too early.

Joss
jocelynl is offline   Reply With Quote
Old 2004-11-28, 13:21   #4
cheesehead
 
cheesehead's Avatar
 
"Richard B. Woods"
Aug 2002
Wisconsin USA

22×3×641 Posts
Default

Quote:
b1 is actually b1+m
No. Prime95 enforces minimum values on b1 and b2, so b1 = b2 = 2 got bumped up. The minimum used to be 30; maybe now it's 60 or more.

27271151 - 1 = 2 × 5^2 × 41 × 53 × 251
cheesehead is offline   Reply With Quote
Old 2004-11-28, 13:28   #5
cheesehead
 
cheesehead's Avatar
 
"Richard B. Woods"
Aug 2002
Wisconsin USA

170148 Posts
Default

Pminus1=79299433,660000,3465000,0,0

This will find any factor of 2^79299433-1 where

factor = 2 * k * 79299433 + 1

and

k has largest factor =< 3465000 and all other factors =< 660000.

Actually, there are stage 2 extensions such that some k with largest factor =< (3465000 * a small integer) will be found, in certain cases.

Last fiddled with by cheesehead on 2004-11-28 at 13:31
cheesehead is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Posts that seem less than useless, or something like that jasong Forum Feedback 1050 2019-04-29 00:50
Fedora gedit for bash has become useless EdH Linux 11 2016-05-13 15:36
Useless SSE instructions __HRB__ Programming 41 2012-07-07 17:43
Useless DC assignment lycorn PrimeNet 16 2009-09-08 18:16

All times are UTC. The time now is 22:00.

Wed Aug 5 22:00:25 UTC 2020 up 19 days, 17:47, 2 users, load averages: 2.12, 1.75, 1.67

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.