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2007-11-04, 14:10   #1
masser

Jul 2003
Behind BB

7×269 Posts
fun with snfs

We have 1 candidate in our dat file with n < 200. If anybody wants to try to factor them, please post here so we don't have duplicate efforts occurring.

Code:
325846*5^159-1 done: p54*p63 (michaf)
322498*5^163-1 done: p47*p74 (michaf)
313126*5^183-1 done: p45*p89 (michaf)
254*5^186-1 done: p57*p77 (michaf)
146264*5^194-1 done: p56*p85 (michaf)

37714*5^172+1 done: p53*p73 (michaf)
24032*5^181+1 reserved      (michaf)
81556*5^184+1 done: p47*p74 (michaf)
Here is the list of all candidates in our dat file with n < 400.

Reservations beyond 200:
Attached Files
 small_n.txt (2.1 KB, 247 views)

Last fiddled with by michaf on 2007-11-09 at 09:32 Reason: less numbers left

 2007-11-04, 17:16 #2 michaf     Jan 2005 1110111112 Posts doing 37714*5^172+1 at this moment
2007-11-04, 22:05   #3
michaf

Jan 2005

479 Posts

37714*5^172+1 done:
Quote:
 Number: 37714_5_172p1 N=63000405172760666624090120201344367236022709460176129121835319112085796466367896466811981959210697823436930775642395019531251 ( 125 digits) SNFS difficulty: 124 digits. Divisors found: r1=14465582032370667658227372663294106255168415715560083 (pp53) r2=4355193246409315121729483588897346062978427046592466831662252772288990497 (pp73) Version: GGNFS-0.77.1-20060513-athlon-xp Total time: 4.63 hours.
Taking 325846*5^159-1

 2007-11-05, 06:31 #4 konrad127123     Jun 2005 2116 Posts I'll have a go at 322498*5^163-1.
2007-11-05, 18:51   #5
michaf

Jan 2005

479 Posts

A nice p54 in there:

Quote:
 Number: 325846_5_159m1 N=445905761139047210246302333785826183313621321008491365394486007844094594852399349171889753051800653338432312011718749 ( 117 digits) SNFS difficulty: 117 digits. Divisors found: r1=946950638415393627493165185410649986962675544483131457 (pp54) r2=470885960735203795153789083353972970130329307107530121167440157 (pp63) Version: GGNFS-0.77.1-20060513-athlon-xp Total time: 2.57 hours.
Reserving 146264*5^194-1

Last fiddled with by michaf on 2007-11-05 at 18:52 Reason: Reservation added

 2007-11-05, 22:59 #6 mdettweiler A Sunny Moo     Aug 2007 USA (GMT-5) 186916 Posts Where would I find a copy of SNFS to possibly try factoring one of these? Or, would the number field sieve (not the quadratic sieve) included with msieve do fine?
 2007-11-05, 23:15 #7 michaf     Jan 2005 479 Posts The numbers are still fine for msieve.Ggnfs is a way quicker with the sieving. (With gnfs the flipover is around 100 digits for my computer, never actually tested that with snfs). You can check for ggnfs at http://tech.groups.yahoo.com/group/ggnfs/ msieve is obtainable at http://www.boo.net/~jasonp/qs.html
2007-11-05, 23:27   #8
mdettweiler
A Sunny Moo

Aug 2007
USA (GMT-5)

3×2,083 Posts

Quote:
 Originally Posted by michaf The numbers are still fine for msieve.Ggnfs is a way quicker with the sieving. (With gnfs the flipover is around 100 digits for my computer, never actually tested that with snfs). You can check for ggnfs at http://tech.groups.yahoo.com/group/ggnfs/ msieve is obtainable at http://www.boo.net/~jasonp/qs.html
Thanks--actually, I already have a copy of the latest version of msieve. I can't quite seem to find where to download ggnfs on the page you listed, though.

Also, how would I go about setting up ggnfs for use with these types of numbers? I've heard it's quite complex and confusing.

2007-11-06, 10:57   #9
michaf

Jan 2005

479 Posts

Oh, my apologies,

the files can be gotten from
http://sourceforge.net/projects/ggnfs/

It's not very easy to set up, but once you are there, the factlat script has most of the work done for you.

Below are the results of my latest snfs-number, the .poly file needs to contain:

n: ....
upto
Y1: ....

Quote:
 Number: 146264_5_194m N=582529988224692499618380406247741498832443291651732985315777101149184326567264847130450243590182000941180007203001878224313259124755859374999 ( 141 digits) SNFS difficulty: 141 digits. Divisors found: r1=97356790107191842626782568435872836358484589585664856887 (pp56) r2=5983455160994060256472046195943542849302859922603898311097732575706621446100614038177 (pp85) Version: GGNFS-0.77.1-20060513-athlon-xp Total time: 13.57 hours. Scaled time: 19.43 units (timescale=1.432). Factorization parameters were as follows: n: 582529988224692499618380406247741498832443291651732985315777101149184326567264847130450243590182000941180007203001878224313259124755859374999 type: snfs skew: 0.12786936592 c5: 146264 c0: -5 Y0: -1818989403545856475830078125 Y1: 1 Name: 146264*5^194-1Factor base limits: 1300000/1300000 Large primes per side: 3 Large prime bits: 26/26 Sieved special-q in [650000, 2450001) Relations: rels:2815184, finalFF:248289 Initial matrix: 200651 x 248289 with sparse part having weight 27234076. Pruned matrix : 195350 x 196417 with weight 17653842. Total sieving time: 12.80 hours. Total relation processing time: 0.11 hours. Matrix solve time: 0.58 hours. Time per square root: 0.08 hours. Prototype def-par.txt line would be: snfs,141,5,0,0,0,0,0,0,0,0,1300000,1300000,26,26,45,45,2.3,2.3,100000 total time: 13.57 hours.
In short, this is how I got there:
146264*5^194-1
I wanted a degree 5 polynomial for this size numbers:
5*146264*5^194-1 = 146264*5^195-5
now, 146264 is c5 (c5 because it's a degree 5 polynomial
-5 is c0
Y0: - 5^(195/5)
Y1: 1
(I'm still confused about which one needs to be negative, but ggnfs seems to prefer Y1 positive :>)
skew: (c0/c5)^(1/5)

On this forum, and on the ggnfs mailinglist a lot of info can be found on how and what, but the best thing to learn from, is from making errors.

2007-11-06, 12:20   #10
xilman
Bamboozled!

"๐บ๐๐ท๐ท๐ญ"
May 2003
Down not across

22·3·941 Posts

Quote:
 Originally Posted by michaf On this forum, and on the ggnfs mailinglist a lot of info can be found on how and what, but the best thing to learn from, is from making errors.
Correction: making errors, thinking about the error messages and attempting to work out what went wrong before even thinking of asking for assistance.

If you can show you've made an honest attempt to correct your errors and are still stuck a number of people here will attempt to help you, even (especially) those who don't suffer fools gladly.

Paul

2007-11-06, 15:47   #11
mdettweiler
A Sunny Moo

Aug 2007
USA (GMT-5)

3×2,083 Posts

Quote:
 Originally Posted by michaf Oh, my apologies, the files can be gotten from http://sourceforge.net/projects/ggnfs/ It's not very easy to set up, but once you are there, the factlat script has most of the work done for you. Below are the results of my latest snfs-number, the .poly file needs to contain: n: .... upto Y1: .... In short, this is how I got there: 146264*5^194-1 I wanted a degree 5 polynomial for this size numbers: 5*146264*5^194-1 = 146264*5^195-5 now, 146264 is c5 (c5 because it's a degree 5 polynomial -5 is c0 Y0: - 5^(195/5) Y1: 1 (I'm still confused about which one needs to be negative, but ggnfs seems to prefer Y1 positive :>) skew: (c0/c5)^(1/5) On this forum, and on the ggnfs mailinglist a lot of info can be found on how and what, but the best thing to learn from, is from making errors.
Whew. Looks tricky. I think I'll stick with the msieve number field sieve for now, though I'll keep your instructions in mind in case I try it out later--thanks!

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