mersenneforum.org  

Go Back   mersenneforum.org > Factoring Projects > GMP-ECM

Reply
 
Thread Tools
Old 2005-04-19, 15:11   #1
wblipp
 
wblipp's Avatar
 
"William"
May 2003
New Haven

93916 Posts
Default Guidelines for ECM Before Other Methods

I have seen guidelines that say that before using GNFS, you should do ECM to 1/3 of the digits. And before doing SNFS, you should do ECM to 2/9 of the digits. For smaller numbers MPQS is better, but I haven't seen any guidelines for how much ECM to do first.

Do people generally agree on the first two guidelines, and what do people recommend for QS?
wblipp is offline   Reply With Quote
Old 2005-04-19, 15:58   #2
xilman
Bamboozled!
 
xilman's Avatar
 
"π’‰Ίπ’ŒŒπ’‡·π’†·π’€­"
May 2003
Down not across

11·967 Posts
Default

Quote:
Originally Posted by wblipp
I have seen guidelines that say that before using GNFS, you should do ECM to 1/3 of the digits. And before doing SNFS, you should do ECM to 2/9 of the digits. For smaller numbers MPQS is better, but I haven't seen any guidelines for how much ECM to do first.

Do people generally agree on the first two guidelines, and what do people recommend for QS?
As long as you realise that the guide lines are only convenient rules of thumb and not the output from rigorous optimization calculations, the first two work well in practice.

I use the 1/3 guideline for MPQS too. These days it doesn't make much sense to use QS much above 100 digits and those take a short time with modern implementations on modern hardware.

All the above assume you know nothing about the factors, other than that there are at least two and that they have not yet been found by trial division and ECM. If you know more about the factors (that they are of comparable size, as in RSA public moduli ,for instance) you need to take that additional information into account.


Paul
xilman is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cyclotomic Polynomial Factoring methods mickfrancis Factoring 2 2015-01-11 18:31
Methods of attacking a large factorization CRGreathouse Factoring 55 2014-04-11 15:05
Very basic question about Wiedemann methods fivemack Math 0 2008-06-16 10:57
Methods to determine integer multiples dsouza123 Math 6 2006-11-18 16:10
performance of primalty check methods juergen Math 2 2004-03-31 21:19

All times are UTC. The time now is 10:50.

Sun Apr 11 10:50:44 UTC 2021 up 3 days, 5:31, 1 user, load averages: 1.89, 1.67, 1.86

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, 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.