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-   -   meta poly for Cxxx ? (https://www.mersenneforum.org/showthread.php?t=24034)

cubaq 2019-01-31 16:26

meta poly for Cxxx ?
 
[FONT=Calibri][SIZE=3]I am working on [URL="http://factordb.com/index.php?id=1100000000634638270"][COLOR=#0000ff]C156[/COLOR][/URL],and at least two other C156 are in line (none of them are special form).[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]I am using yafu without Msieve (ini file below).[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]Is it possible to use some existing poly dedicated for C156 (I.E. [URL="https://www.mersenneforum.org/showthread.php?t=16205"][COLOR=#0000ff]this one[/COLOR][/URL]) and decrease sieve time[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]instead of spending another ~35 CPU-hours to find one.[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]If not - how it will fail: at once, during sieve, atlinear, or (not this one please) in sqrt stage.[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]If yes - how to create nfs.dat.p entry when values of norm,alpha and rroots are unknown; I would create nfs.job and nfs.fb myself but why the poly's in those files are different.[/SIZE][/FONT]


[FONT=Calibri][SIZE=3]Thanks in advance,[/SIZE][/FONT]

[FONT=Calibri][SIZE=3]cubaq[/SIZE][/FONT]

[FONT=Calibri][SIZE=3]PS. yafu.ini:[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]B1ecm=11000[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]B1pm1=100000[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]B1pp1=20000[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]rhomax=1000[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]threads=8[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]pretest_ratio=0.25[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]%ggnfs_dir=D:\ggnfs\[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]ggnfs_dir=D:/ggnfs/[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]R=1[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]%ecm_path=..\Gmp-Ecm\ecm.exe[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]ecm_path=..\Gmp-Ecm\ecm[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]tune_info= Intel(R) Xeon(R) CPU E5-4650 0 @2.70GHz,LINUX64,1.73786e-05,0.200412,0.400046,0.0987873,98.8355,2699.98[/SIZE][/FONT]


[FONT=Calibri][SIZE=3]session.log (partial)[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]01/31/19 11:53:07 v1.34.5 @ WLODEK-KOMPUTER,System/Build Info: [/SIZE][/FONT]
[FONT=Calibri][SIZE=3]Using GMP-ECM 6.3, Powered by GMP 5.1.1[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]cached 78498 primes. pmax = 999983[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]detected Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]detected L1 = 32768 bytes, L2 = 8388608 bytes, CL = 64bytes[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]measured cpu frequency ~= 3565.667100[/SIZE][/FONT]
[FONT=Calibri][SIZE=3]using 20 random witnesses for Rabin-Miller PRP checks[/SIZE][/FONT]

firejuggler 2019-01-31 17:04

Unfortunately, poly are composite specific. So it will crash imediately.
As for finding a poly, you can ask for one in this thread

[url]https://mersenneforum.org/showthread.php?t=18368[/url] The trouble is that it will take around 24H to get a 'decent' usable poly. As for how to create nfs.dat.p and the other file, I do not know.

VBCurtis 2019-01-31 17:46

Pretest ratio of 0.25 is really low; for a C156 you ought to do at *minimum* a T45 worth of ECM. I'd do half a T50 before GNFS, personally. (Or maybe I misunderstand what pretest ratio is)

That's about a 6-desktop-core-week job to run through GNFS; spending 1.5 days on poly select is likely about right. If you get a score within 10% of the record poly score for that size, it's "good enough". If you don't have a GPU to use with msieve, the CADO tools produce very nice polys from CPU searches.

Trying to use a poly from a different input will crash GNFS immediately with error "poly does not divide N!" or similar.

cubaq 2019-02-01 12:26

Thank You both for reply


@firejuggler:

While using 'other' poly will crash, that knowlege seems to be pointless.




@VBCurtis:

Pretest ratio does not control upper limit of ECM stage. From the other hand, I am using ecm directly (yes up to ~T50 for C156).

How do You measure that kind of percentage (i.e. i have e 1.952e-012 for C156 - is it good enough?).
As far CADO I've just start to learn "How To …" so it'l take some weeks: do I really may ask for proper poly for C156,C157 on forum?


Thanks once more,


cubaq

cubaq 2019-02-01 15:25

@firejuggler:



I am terrible sorry, I've just realize how that may be read. I ment the last sentence of Your reply. Sorry once more.


cubaq.

VBCurtis 2019-02-01 16:34

[QUOTE=cubaq;507323]
How do You measure that kind of percentage (i.e. i have e 1.952e-012 for C156 - is it good enough?).
As far CADO I've just start to learn "How To …" so it'l take some weeks: do I really may ask for proper poly for C156,C157 on forum?
[/QUOTE]
The record for a C156 is 2.893e-12; for C157 it's 2.776e-12. That means 2.5 to 2.6e-12 should be reachable with a day or two of GPU-msieve.

The poly you've found would take roughly 25% longer to sieve than one with the score I've estimated (the ratio of the scores is roughly the inverse ratio of sieving times). It's worth spending a few days on poly select to save ~1.5 core-weeks of sieving!


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