mersenneforum.org  

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

Reply
 
Thread Tools
Old 2020-02-05, 11:22   #23
axn
 
axn's Avatar
 
Jun 2003

22×5×239 Posts
Default

Quote:
Originally Posted by R.D. Silverman View Post
Did I gore your ox, too?
axn is offline   Reply With Quote
Old 2020-02-05, 13:38   #24
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

26×113 Posts
Default

Quote:
Originally Posted by LaurV View Post
Our goal was not to get the fastest factoring method, but to show that even such non-efficient stuff like TF (which is in fact what Mr. Cole used) would factor M67 in "milliseconds" in an average computer. That is what the OP wanted to know.
Which is what I said. I did not specify a particular method.
R.D. Silverman is offline   Reply With Quote
Old 2020-02-05, 14:45   #25
xilman
Bamboozled!
 
xilman's Avatar
 
"π’‰Ίπ’ŒŒπ’‡·π’†·π’€­"
May 2003
Down not across

5×2,039 Posts
Default

Quote:
Originally Posted by R.D. Silverman View Post
I did say "a few milliseconds". But of course, no one listens.
People were listening.

Trust, but verify, as Ronnie would say.
xilman is offline   Reply With Quote
Old 2020-02-05, 14:45   #26
Uncwilly
6809 > 6502
 
Uncwilly's Avatar
 
"""""""""""""""""""
Aug 2003
101Γ—103 Posts

5·1,777 Posts
Default

Quote:
Originally Posted by R.D. Silverman View Post
Which is what I said. I did not specify a particular method.
And for the OP's benefit they are actually showing real world examples to demonstrate this. No need to get your knickers in a knot. You should be thanking them for demonstrating this conclusively to the OP.
Uncwilly is offline   Reply With Quote
Old 2020-02-05, 15:27   #27
LaurV
Romulan Interpreter
 
LaurV's Avatar
 
Jun 2011
Thailand

22E416 Posts
Default

Quote:
Originally Posted by R.D. Silverman View Post
Which is what I said. I did not specify a particular method.
I was replying to CRG, about "willing to optimize". In fact I was in agreement with you all the way, if you look carefully. Don't be sad, no one listens to me either (I mean, generally, not in this topic), my life's drama...

Better lock this topic before sparks get to flames...
The OP got his answer already.

Last fiddled with by LaurV on 2020-02-05 at 15:31
LaurV is offline   Reply With Quote
Old 2020-02-06, 03:55   #28
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

2×2,969 Posts
Default

Quote:
Originally Posted by LaurV View Post
Pari, Trial Factoring with 420 classes (script posted here in the past), slow/moderate laptop (i5-3340M at 2.7GHz)
I found a reference to it in a previous thread of mine, but I can't find the script on these forums or elsewhere on the web. Could you post it, please?
CRGreathouse is offline   Reply With Quote
Old 2020-02-06, 04:26   #29
LaurV
Romulan Interpreter
 
LaurV's Avatar
 
Jun 2011
Thailand

213448 Posts
Default

That is easy, because I got recently into a PM exchange with Hans Loeblich who extended my script for more classes and made it faster and parallel, and that is easy to find, I try to keep my PM list in order hehe... All the links are there, in that thread (edit2: posts from #32 to #52 and after, the script is attached to post #52 -- interesting that the examples provided there were exactly for M67, haha)

Edit: I reopened the topic, as long as the argument continues , it didn't feel right that only the mods can post, and other users have to right to reply if they choose so.

Last fiddled with by LaurV on 2020-02-07 at 08:51
LaurV is offline   Reply With Quote
Old 2020-02-06, 21:07   #30
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

134628 Posts
Default

Thank you.

By the way, why 420 instead of 210?
CRGreathouse is offline   Reply With Quote
Old 2020-02-07, 03:05   #31
axn
 
axn's Avatar
 
Jun 2003

22×5×239 Posts
Default

Quote:
Originally Posted by CRGreathouse View Post
By the way, why 420 instead of 210?
There are two classes, 1 and 7 (mod 8)

Last fiddled with by axn on 2020-02-07 at 03:05
axn is offline   Reply With Quote
Old 2020-02-07, 05:28   #32
LaurV
Romulan Interpreter
 
LaurV's Avatar
 
Jun 2011
Thailand

213448 Posts
Default

Quote:
Originally Posted by CRGreathouse View Post
Thank you.
By the way, why 420 instead of 210?
Because making it multiple of 4 helps a lot when eliminating classes of k which would result in factors q=2kp+1 being 3 and 5 (mod 8). If the number of classes are 4, 12, 60, 420, 4620 (the double primorials, instead of 2, 6, 30, 210, 2310), then for some k and p, will have q already in the right class (mod 8).

For example: if p is 3 (mod 4) and k is 15 (mod 420), therefore k is 3 (mod 4) (here, you could not say that, in case of k in 210 classes! You would have no information about modularity of k to 4, as 210 is not multiple of 4), therefore q is 2*3*3+1=19 (mod 8, due to the 2 in front, you can double the modulus here), which is 3 (mod 8) and so, when p=3 (mod 4), you can completely eliminate the class k=15 (mod 420), due to the fact that all mersenne factors must be 1 or 7 (mod 8). When p=3 (mod 4), there is no factor q=2kp+1 with k=15 (mod 420). This is how you get from 4620 classes to only 960 to test for each p, or respectively, from 420 to only 96.

That's why. This doubles the testing speed. See those 3 posts of mine in the linked thread where I explained. The idea is not mine, it comes from Oliver and the forum (there are antique discussions from when he was developing mfaktc, in mfaktc thread and archieves).

Last fiddled with by LaurV on 2020-02-07 at 05:58 Reason: grr...hating the multipl empty lines between paragraphs...
LaurV is offline   Reply With Quote
Old 2020-02-07, 06:33   #33
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

2·2,969 Posts
Default

Thanks!
CRGreathouse is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Got an email from prof. Keller ET_ FermatSearch 2 2016-11-03 17:00
big factor lfm Data 15 2010-03-30 21:18
New factor fivemack ElevenSmooth 4 2008-05-07 19:28
Prime 95 + BSOD issues Win xp Prof sp2 matt00926 Hardware 3 2005-03-16 00:15
Shortest time to complete a 2^67 trial factor (no factor) dsouza123 Software 12 2003-08-21 18:38

All times are UTC. The time now is 05:22.

Sat Nov 28 05:22:51 UTC 2020 up 79 days, 2:33, 3 users, load averages: 1.24, 1.62, 1.56

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.