20130723, 04:54  #67 
Sep 2008
Kansas
2×31×53 Posts 
A Challenge
Aliquot Sequence 4788 sits at index 5154 with a c173 remaining. The best poly found so far is posted at: http://mersenneforum.org/showpost.ph...postcount=2102.
This is a very, very low request but can this poly be bettered? I believe the leading coefficient has been tried through 800K. 
20130723, 05:27  #68 
Apr 2010
Over the rainbow
2×5×11×23 Posts 
I will try.

20130724, 21:57  #69 
"Curtis"
Feb 2005
Riverside, CA
2×2,339 Posts 
Another poly for Tom's C176:
Code:
n: 23847813234751095518553790092375554156554053397317779773831395300907022889988067196688707035368393323174109573706580716877436977083912429179428455659750299481884888866554791173 # norm 3.445278e017 alpha 6.820795 e 1.321e013 rroots 5 skew: 3088331.89 c0: 498014898833129675206187724146860356135 c1: 24249301299856929460089682902161763 c2: 34320331326371745034488026956 c3: 7376626463852947241062 c4: 3051637511514764 c5: 214785480 Y0: 2565008026979220326617490926563632 Y1: 186995647017448237 
20130724, 22:04  #70 
I moo ablest echo power!
May 2013
1,741 Posts 
Stupid question about trialsieving:
Is that essentially seeing how many relations/sec one gets with a given polynomial? 
20130724, 22:52  #71  
Jun 2012
3^{2}·7·47 Posts 
Quote:
ETA: See this thread for a discussion on sieving estimates. Last fiddled with by swellman on 20130724 at 23:26 Reason: Link added 

20130725, 00:35  #72 
Tribal Bullet
Oct 2004
DCE_{16} Posts 
Trial sieving is supposed to try minimizing the time that sieving needs to complete. That means picking the size and number of large primes, estimating the number of relations that would be needed from that, then sieving a few widely separated Q values (say 1/1000 of the complete job) and computing the estimated total sieving time giving the relations/sec found across each range.
It amazes me that folks here have the discipline to manage fullscale trial sieving for any job. I don't think I could do it. 
20130725, 01:01  #73 
I moo ablest echo power!
May 2013
1,741 Posts 
Man, you're not kidding. Might be interesting to play around with, but at this point, I think I'm limited more by not having a cluster (quad core laptop processor! woooooo!) to use for the sieving rather than tweaking the parameters for optimization.

20130725, 01:26  #74 
"Curtis"
Feb 2005
Riverside, CA
2×2,339 Posts 
I, too, have an i7 laptop as my factoring tool. You're mostly right about trialsieving mattering less for us if, say, 3 humanhours spent on optimizing parameters can save 10% of a job's sieve length, we'd have to be running a very lengthy job (or REALLY treasure our CPU time vs our human time) for the trial time to be worthwhile.
But as one moves up into GNFS150s, the prospect of 10% saved can mean days of CPU time; not to say we'll automatically find 10% efficiency... Further, it strikes me that one ought to learn which knobs to turn to attempt to optimize when the cost of a mistaken "optimization" is days rather than weeks. When I do get around to tackling a GNFS150, I plan to try just this even though best parameters are well known (?)in the 150s. Do enough people use the factmsieve script for 150+ factorizations that we (I volunteer) should update the parameters files? 
20130725, 01:44  #75  
Jun 2012
101110010001_{2} Posts 
Quote:
Start hunting big game (e.g. GNFS 190s) and things are much different. Sieving jobs can take CPUcenturies. All IMHO of course. 

20130725, 01:54  #76  
Jun 2012
3^{2}·7·47 Posts 
Quote:


20130725, 15:51  #77  
I moo ablest echo power!
May 2013
1,741 Posts 
Quote:
I hope that one day soon we'll be able to sieve using a CUDAbased system. That would be fantastic. 

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