mersenneforum.org  

Go Back   mersenneforum.org > Factoring Projects > NFS@Home

Reply
 
Thread Tools
Old 2018-12-03, 00:30   #1
RichD
 
RichD's Avatar
 
Sep 2008
Kansas

32×347 Posts
Default Parametrization Assistance

The top 12th number in the MWRB file has an OPN weight of 2.5M (2465207). It is ready for SNFS. With an SNFS difficulty of 281.5 it seems to be within reach using the 15e queue.

I have little to no experience at this level. What are the best parameters if it could be sieved using 15e?

Code:
n: 605716904027877980774625455520189647387776352555063757365644672493136637525085152114527251672682055452329862008130550673203343550128250999766605061023948523297828457779191592093682881010498969046911261346842026672855745883554109771998292748069377018429964450347583969787
# 732541^47-1, difficulty: 281.51, skewness: 9.49, alpha: 0.00
# cost: 8.45884e+19, est. time: 40280.21 GHz days (not accurate yet!)
skew: 9.494
c6: 1
c0: -732541
Y1: -1
Y0: 82919274927962023982932249248351337261442889121
m: 82919274927962023982932249248351337261442889121
type: snfs
RichD is offline   Reply With Quote
Old 2018-12-03, 04:12   #2
VBCurtis
 
VBCurtis's Avatar
 
"Curtis"
Feb 2005
Riverside, CA

22·1,091 Posts
Default

I'd try test-sieving alim=rlim=268M, 33LP, 3 large primes on one side (I forget which side to expect to be better, but one test-Q range on each should make it clear).

I'd use 95 and 65 as the lpbr and lpba (or vice versa, depending on which is 3LP side). If yield is above 2.5, you could consider doing a 32/33 hybrid, or dropping the lim on the sieved side to 200M to save memory and maybe squeeze out a bit better sec/rel.
VBCurtis is offline   Reply With Quote
Old 2018-12-03, 04:33   #3
swellman
 
swellman's Avatar
 
Jun 2012

287010 Posts
Default

I agree the sweet spot is 33-bit LP on 15e.

Besides the suggested parameters given by VBCurtis, you might want to try a/rlim=536M, and variants on that theme (e.g. 3 LP on one side, mixed alim/rlim, etc.). You’re up in thin air with this job - not many tread up here. Test sieving should show the path forward.
swellman is offline   Reply With Quote
Old 2018-12-03, 05:38   #4
RichD
 
RichD's Avatar
 
Sep 2008
Kansas

60638 Posts
Default

Thanks for all the feedback. It looks like a lot of test sieving as I expected.

I thought I saw some "non-traditional" parameters like lambda=3.0 for 15e which didn't look familiar. Perhaps a hybrid sieve might be worthwhile. I've had mixed results with those. Then again, I'm not that fluent with cross pollination. Back to the salt mines.
RichD is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Factoring GCW numbers - call for assistance. xilman Factoring 181 2016-07-03 14:32
Moderator assistance Jim White Forum Feedback 0 2007-08-31 05:01

All times are UTC. The time now is 11:08.

Tue Oct 20 11:08:16 UTC 2020 up 40 days, 8:19, 0 users, load averages: 1.89, 2.15, 2.09

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.