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 2021-12-02, 17:28 #100 bur     Aug 2020 79*6581e-4;3*2539e-3 7678 Posts How to proceed (sieve, LLR, P-1) depends on which method removes candidates faster. For sieving that's a bit hard to determine since it removes an n=10M almost as fast as n=1M while the LLR of the former takes 100 times more. For P-1 vs LLR it's easy though. Just time how long LLR takes to remove 10 candidates and how long P-1 would take in the same range. I strongly suspect P-1 doesn't make sense. It's only useful for Mersennes because they are so large and have those specially formed factors including the exponent. Here's how I do it: do a few LLR tests and write down the average time. Then sieve for 1-2 days and see if that removes candidates faster or not. If yes, continue sieving, if not, continue LLR until an LLR test again takes longer to remove a candídate than sieving did.
2021-12-02, 18:25   #101
ValerieVonck

Mar 2004
Belgium

15158 Posts

Quote:
 Originally Posted by bur How to proceed (sieve, LLR, P-1) depends on which method removes candidates faster. For sieving that's a bit hard to determine since it removes an n=10M almost as fast as n=1M while the LLR of the former takes 100 times more. For P-1 vs LLR it's easy though. Just time how long LLR takes to remove 10 candidates and how long P-1 would take in the same range. I strongly suspect P-1 doesn't make sense. It's only useful for Mersennes because they are so large and have those specially formed factors including the exponent. Here's how I do it: do a few LLR tests and write down the average time. Then sieve for 1-2 days and see if that removes candidates faster or not. If yes, continue sieving, if not, continue LLR until an LLR test again takes longer to remove a candídate than sieving did.

1. I have retested the primes found by gd_barnes : they are confirmed
2. On my i3 I am sieving the input from gd_barnes to 260T: eta 03/22
3. On my i5 imac I am llr’ing the range 1.3m to 1.4m each candidate takes 733 seconds
4. Sieving on that latest machine I am eliminating a candidate each 500 - 550 seconds
4.1. On a sidenote gd_barnes Saïd to me you are missing factors due to a wrong setting in NewPgen, my file ranges from 1.3m to 50m and I already sieved to 260T … taking this up from the beginning will take also take time
5. I will take a stab at p-1 when my current range is done or will try it on my i7 portable (laptop)

Ftm I am recovering from a mild Covid infection

Kind regards,
Valerie

 2021-12-03, 01:51 #102 VBCurtis     "Curtis" Feb 2005 Riverside, CA 527910 Posts If you're going to LLR test the entire file, then one should sieve until the factor-removal rate is half as fast (twice the seconds per factor) as an LLR test takes for the smallest candidate in the file. This is due to the way the sieve scales- when you take candidates out of the sieve for LLR, the sieve speed does not change linearly. Since there is not much speed to be gained by taking candidates out, we leave the small candidates in longer than common-sense might suggest. A rough scaling example: If you take out 10% of the candidates from the sieve file, the sieve only runs ~5% faster ("faster" as measured by p/sec).
 2021-12-08, 05:20 #103 ValerieVonck     Mar 2004 Belgium 5×132 Posts I gathered a few statistics: - Sieving yields a factor each 552 seconds - An llr test takes 735 seconds for the range 1.3M -> 1.4M (which I am currently busy testing) - A P-1 test takes 30 minutes, with bounds B1 = 1M - An ECM test takes 30 minutes for each curve, with bounds B1 = 1M For the moment, I will complete the range 1.3M -> 1.4M Kind regards, Valerie
 2022-01-23, 09:28 #104 Happy5214     "Alexander" Nov 2008 The Alamo City 2×401 Posts P-1 is useless for Riesel candidates for the reasons bur listed. In fact, your tested B1 of 1M is higher than what GIMPS recommends even for wavefront (i.e. p~105M) Mersenne candidates (which is in the 800k range on my computer). Bounds that high are only used on numbers in the 1.3M-bit range when we're trying to (partially) factor it, not pretest before running a primality test.

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