20121026, 00:34  #2 
Mar 2006
Germany
3^{3}·107 Posts 
The zipfile is not readable.

20121026, 01:03  #3 
"Ben"
Feb 2007
3438_{10} Posts 
Things acted a bit funny when I first uploaded it. I reuploaded, so try it again.
thanks. 
20121107, 03:29  #4 
Jun 2012
2^{3}·3·5^{3} Posts 
SNFS # of relations?
When "type: SNFS" is added to the nfs.job file, the estimated required number of relations seems higher than I had been led to expect from SNFS.
What's the formula for this estimate? Also the # rels/spec_q ratio for my poly drops horribly when changing type from GNFS to SNFS (and the estimated time goes up), despite the usual rule of thumb recommending use of SNFS for my composite. Didn't expect that. Maybe I'm comparing apples and oranges here... 
20121107, 03:40  #5  
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
16065_{8} Posts 
Quote:
Code:
(2*fudge * (pow(2.0,(double)lpb) / log(pow(2.0,(double)lpb)))) Code:
case 27: fudge = 0.70; break; case 28: fudge = 0.76; break; case 29: fudge = 0.84; break; case 30: fudge = 0.89; break; case 31: fudge = 0.91; break; Quote:
Last fiddled with by Dubslow on 20121107 at 03:41 Reason: 2*fudge 

20121107, 03:50  #6 
Jun 2012
2^{3}×3×5^{3} Posts 
I use snfs in my poly (and Yafu recognizes it as such). It was just all caps here due to my silly iPhone autocorrect.
Will post my example tomorrow to show specifics. Thanks for the formula. 
20121107, 04:00  #7  
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
7221_{10} Posts 
Quote:
Actually, do you have the "size: 190" (or whatever) in your job file? If you don't, YAFU assumes the SNFS difficulty is the size of the n: in the job file, and if there are other known factors those two sizes could be significantly different. 

20121107, 21:01  #8  
Jun 2012
2^{3}·3·5^{3} Posts 
Quote:
As to estimating the number of relations required for SNFS, I had been using models from Kamada's site. For SNFS, they use 4*10^(d/70+4) where d is the SNFS difficulty. The other parameters for a poly file are also modeled on that page, presumably based on successful factorizations. Anybody have a feel for how accurate the Kamada models are? 

20121107, 21:59  #9  
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
1C35_{16} Posts 
Quote:
Quote:
As for the regression you quote, that's due to the fact that the choice of lpb is pretty well understood (read: consistent) for difficulties <= ~250 (and in turn the min_rels estimate is consistent). Last fiddled with by Dubslow on 20121107 at 22:04 

20121107, 22:59  #10 
Jun 2012
2^{3}×3×5^{3} Posts 
Example
Posting my example, which still has an odd warning message about ignoring the size parameter, even though Yafu appears to use it. But with the size parameter in place, things seem much better.
Composite is C163_145_33 from the xyyx project. It has a SNFS difficulty of 221. My poly is as follows Code:
n: 8044748335384450433189067533289903349948378898702376138454639872609531665263335556364761169996899460279132119953474639118706796845849163688530204021522714077427337 type: snfs size: 221 skew: 19.81 c0: 3048625 c5: 1 Y0: 108869005682301795684211705446369982097742753 Y1: 9294114390625 rlim: 34000000 alim: 34000000 lpbr: 29 lpba: 29 mfbr: 58 mfba: 58 rlambda: 2.600000 alambda: 2.600000 Code:
c:>yafu "nfs(8044748335384450 43318906753328990334994837889870237613845463987260953166526333555636476116999689 9460279132119953474639118706796845849163688530204021522714077427337)" v r R  ns 15000000,15001000 11/07/12 17:37:10 v1.33 @ NATINB84202, System/Build Info: Using GMPECM 6.3, Powered by GMP 5.0.1 detected Intel(R) Core(TM)2 Duo CPU P8700 @ 2.53GHz detected L1 = 32768 bytes, L2 = 3145728 bytes, CL = 64 bytes measured cpu frequency ~= 2419.123890 using 20 random witnesses for RabinMiller PRP checks =============================================================== ======= Welcome to YAFU (Yet Another Factoring Utility) ======= ======= bbuhrow@gmail.com ======= ======= Type help at any time, or quit to quit ======= =============================================================== cached 78498 primes. pmax = 999983 >> nfs: checking for job file  nfs: number in job file matches input nfs: checking for data file nfs: no data file found nfs: commencing nfs on c163: 804474833538445043318906753328990334994837889870237 61384546398726095316652633355563647611699968994602791321199534746391187067968458 49163688530204021522714077427337 nfs: found type: snfs nfs: found size: 221 nfs: parsed lpbr = 29, lpba = 29, type = snfs, setting lpb = 29 nfs: guessing snfs difficulty 221 is roughly equal to gnfs difficulty 153 nfs: continuing with sieving at user specified specialq 15000000 nfs: commencing rational side lattice sieving over range: 15000500  15001000 nfs: commencing rational side lattice sieving over range: 15000000  15000500 Warning: Ignoring input line: size: 221 Warning: Ignoring input line: size: 221 Warning: lowering FB_bound to 15000499. Warning: lowering FB_bound to 14999999. total yield: 1057, q=15001001 (0.32842 sec/rel) total yield: 1073, q=15000509 (0.34927 sec/rel) found 2130 relations, need at least 44869960 (filtering ETA: 2263h 37m), continu ing with sieving ... ***factors found*** ***cofactor*** C163 = 8044748335384450433189067533289903349948378898702376138454639872609531665 26333555636476116999689946027913211995347463911870679684584916368853020402152271 4077427337 ans = 80447483353844504331890675332899033499483788987023761384546398726095316652 63335556364761169996899460279132119953474639118706796845849163688530204021522714 077427337 
20121107, 23:45  #11 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
3×29×83 Posts 

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