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Old 2020-05-22, 07:46   #496
(loop (#_fork))
fivemack's Avatar
Feb 2006
Cambridge, England

2·11·172 Posts
Default L4375B done

This popped up on the page and I managed to complete it in three real-time weeks on one machine (I'll admit it was an i9-7940X so quite a fast machine) - 2.5 days polynomial search, a bit of a gap while other jobs finished and I did the trial sieving, 12 days sieving, 1 day linear algebra.

32-bit LP, three algebraic large primes, alim=rlim=5e7, sieve Q=25M-75M (which is nice and round, but was determined by looking at yields incrementally rather than entirely in advance)

Notice how smooth the yield curve is when corrected for ideal count, and how the peak here is at alim. With this extra smoothness reasonable-sized trial sieving gives much more credible numbers; I'm not sure I'd have used 3lpa for things this small but it was clearly several percent better in the trial-sieve.

Expecting baby before next factor :)
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Last fiddled with by fivemack on 2020-05-22 at 07:47
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Old 2020-05-25, 15:33   #497
chris2be8's Avatar
Sep 2009

3×631 Posts

Originally Posted by fivemack View Post
Notice how smooth the yield curve is when corrected for ideal count
Can you confirm the ideal count is the first number on the following line output by gnfs-lasieve4I14e (in this case over a range of 10k special-Q):
522 Special q, 3933 reduction iterations
If that's true how many ideals should I assume per 10M special-Q? This would be a big help trial sieving numbers for NFS@Home.

Thanks in advance.

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Old 2020-06-11, 16:51   #498
Apr 2020

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Lucky ECM hit, from 3+2_1842M from the HCN tables:

GMP-ECM 7.0.5-dev [configured with GMP 6.2.0, --enable-asm-redc, --enable-assert] [ECM]
Input number is 2575167245145580345545358603140126953887375815021234731765984191692079396591260156613577262910448277094539273838808805370857935219624918675016962379584174887505043190773944811610010073257320929688633424357191886761888329736734042381290881 (238 digits)
Using B1=110000000, B2=776278396540, polynomial Dickson(30), sigma=1:2166799276
Step 1 took 304804ms
Step 2 took 88190ms
********** Factor found in step 2: 1881941120468249708169539576246651193369513480043229827729929343069
Found prime factor of 67 digits: 1881941120468249708169539576246651193369513480043229827729929343069
Prime cofactor 1368356967780611326835948661781737382237519565564396399185048685206843247071058939238469661163518378115591947475004902031363212895011322108712962118435289831026432120434549 has 172 digits
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Old 2020-09-05, 09:00   #499
Happy5214's Avatar
Nov 2008
The Alamo City

37510 Posts

This is (AFAIK) my personal ECM record:

122760214563986517403408012718327323026952918039831060056060998708807150488395908248657867219215800100789370303292314531669 = 85548851675281967428710863747045885644186850007163 * 1434972090916519038274518487801044320499147038941606461183097450445450863 (21^76:i208).

This P50 was found in just 410 curves at B1=3M. I lack patience and my hardware is really old, so this saved the sequence from exceeding the self-imposed C120 cofactor limit for NFS.
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