[QUOTE=VBCurtis;456229]I use alim/4 for GNFS and alim/6 for SNFS, subject to a minimum starting value of 5M and maximum starting value of 25M. For small (say, a core-week or less) projects, I use alim/3 for GNFS and alim/4 for SNFS.

BOINC seems to start at 20M pretty regularly, and I don't think it matters a whole lot whether one chooses 15M or 20M or 25M to start when alim/rlim are 100M+, so 20M has become a sort of de facto standard for all but the largest projects.

In the past, it was believed that the faster sec/rel times at small Q were illusions because of higher duplicate rates, but I think that has been debunked in the alim/5 to alim/2 region.[/QUOTE]

Thank you for the information. Yes, the higher duplicate rate at low Q was one of the warnings I'd read, but if it's a myth then so be it.

I'm curious - is there a quick rule of thumb for modeling the decreasing yield curve over a large range of Q for an accurate estimate of the sieving range? Or is that more art? I'm good at modeling such things but it can be time consuming, so if there's a quick-but-good-enough method then I'm all ears!

P21.14943_13M.C206 is ready.
[CODE]n: 89565020195209009565467987087523777190165220963732300333632805305657311963519775871355884908105015698333537785557847431074271876592471825692366680584078161538467475749662494429667299122846947799699591673579
# 149431854123332538041^13-1, difficulty: 242.09, skewness: 1.00, alpha: 3.10
# cost: 4.51385e+18, est. time: 2149.45 GHz days (not accurate yet!)
skew: 1.000
c6: 1
c5: 1
c4: -5
c3: -4
c2: 6
c1: 3
c0: -1
Y1: -149431854123332538041
Y0: 22329879026736935651195230967634712117682
m: 23565865290286569388823858250238266971263782880320796060116123560770899985421941989827510445870492077635584653040018904191599893740867088229038460402604998044704586084004555217759935764696304299260298567603
type: snfs
rlim: 120000000
alim: 120000000
lpbr: 31
lpba: 31
mfbr: 62
mfba: 62
rlambda: 2.6
alambda: 2.6[/CODE]
Trial sieve 5K blocks.
[CODE] Q Yield
20M 12416
50M 10525
80M 8962[/CODE]

Another 14e
 

C209_122_107 is nearing completion of t55 by yoyo@Home.


[code]
n: 45593358642996478364538112111174968061772662806395817785620327515809295803708534368841966179066170869564093890043051507627396767585413436241604695929929618429387862507149811619032959373562170721399964592363601
# 122^107+107^122, difficulty: 247.58, anorm: 2.36e+039, rnorm: -1.26e+047
# scaled difficulty: 248.87, suggest sieving rational side
# size = 8.302e-013, alpha = 0.000, combined = 1.075e-013, rroots = 0
type: snfs
size: 247
skew: 10.5727
c6: 1
c0: 1396778
Y1: -38696844624861790832365403138487376998001
Y0: 35848992283832616457430560986334756864
rlim: 250000000
alim: 250000000
lpbr: 32
lpba: 32
mfbr: 64
mfba: 64
rlambda: 2.8
alambda: 2.8
[/code]

Test sieving gives the following yields
[code]
1.90 @Q=40M
1.64 @Q=100M
1.21 @Q=180M
1.22 @Q=250M
1.01 @Q=370M
[/code]

Which leads me to believe the sieving range is 40-450M.

13*2^793-1:
[code]# 13*2^793-1 difficulty: 240
n: 245459994333326919443410901346097158174068960121046154069468560261450530982369518932964157573944452706561200577507849282111043339664498382619421553516587020088145546714743668816094603954681579
m: 5444517870735015415413993718908291383296
type: snfs
skew: 1.72
c6: 26
c0: -1
rlim: 110000000
alim: 110000000
lpbr: 32
lpba: 32
mfbr: 64
mfba: 64
rlambda: 2.7
alambda: 2.7[/code]
ECM'ed to half a t55.
Q of 20M to 120M should be sufficient for me to run the LA, same range as was run on 13*2^792-1. Avg yield is near 3.4, and 340M rels is enough to build a matrix for these numbers.
I'm not yet fully certain I have skew calculations correct; I did 26^(1/6) for this skew. Is that right, or should skew be the reciprocal of that?

[quote]I'm not yet fully certain I have skew calculations correct; I did 26^(1/6) for this skew. Is that right, or should skew be the reciprocal of that?[/QUOTE]

Skew should be the reciprocal of that - to remember that, remember that GNFS polynomials have large skew, and have the constant term much larger than the leading coefficient.

Skew inverted, polynomial queued

Queued C209_122_107, 13_2_793m and C206_149xx041_13

[QUOTE=fivemack;456403]Skew should be the reciprocal of that - to remember that, remember that GNFS polynomials have large skew, and have the constant term much larger than the leading coefficient.

Skew inverted, polynomial queued[/QUOTE]

Thanks! Looks like inverting skew improved yield by 25%. Good thing I didn't even edit skew from 1.0x for the first couple years I factored these numbers; I would have edited it the wrong direction!

Downloading relations now.

@VBCurtis @fivemack
You can get a bit higher E score if you set skew=0.75 instead of skew=0.58:
[code]
Msieve v. 1.53 (SVN unknown)
random seeds: 2db15a70 021c94d2
factoring 245459994333326919443410901346097158174068960121046154069468560261450530982369518932964157573944452706561200577507849282111043339664498382619421553516587020088145546714743668816094603954681579 (192 digits)
no P-1/P+1/ECM available, skipping
commencing number field sieve (192-digit input)
R0: -5444517870735015415413993718908291383296
R1: 1
A0: -1
A1: 0
A2: 0
A3: 0
A4: 0
A5: 0
A6: 26
skew 0.75, size 8.995e-012, alpha 0.805, combined = 5.873e-013 rroots = 2
[/code]Obtained from [URL]http://myfactors.mooo.com/[/URL] (Optimal Skew)

Any more candidates for 14e? The queue is once again running dry.

I should have one posted later today but more are needed.

14e
 

C209_127_91 has nearly completed a full t55 (85.6% complete at the time of this posting) by yoyo@Home.

[code]
n: 26940995360358453137720369146025885289223140375197877977981639330991363717529250240230037034188430266450967981323191907750900799884059432559083059910290611501303668882237162459786057340251559518931079556646633
# 127^91+91^127, difficulty: 250.76, anorm: 2.15e+038, rnorm: 1.34e+047
# scaled difficulty: 252.22, suggest sieving rational side
# size = 1.141e-012, alpha = 0.000, combined = 1.346e-013, rroots = 0
type: snfs
size: 250
skew: 1.0571
c6: 91
c0: 127
Y1: -36062498658084837781704007862143
Y0: 137996870875659993023030601717979081222891
rlim: 240000000
alim: 240000000
lpbr: 32
lpba: 32
mfbr: 64
mfba: 64
rlambda: 2.8
alambda: 2.8
[/code]

Some test sieving on blocks of 1000 Q, hope this is in a more user friendly form
[code]
yield: 2836, q=20001001 (0.49325 sec/rel)
yield: 1602, q=140001013 (0.65194 sec/rel)
yield: 1465, q=260001013 (0.88608 sec/rel)
[/code]

86353_47M.C185 is ready.
[CODE]n: 28448940404495058815836669391775762163760283231206204352120421742419083638829799923679271303255141623796529822942824468873818526386945481411116502483777554312314040915730295977513616383
# 86353^47-1, difficulty: 236.94, skewness: 6.65, alpha: 0.00
# cost: 3.01467e+18, est. time: 1435.56 GHz days (not accurate yet!)
skew: 6.648
c6: 1
c0: -86353
Y1: -1
Y0: 3091857291722705477037327063091586156161
m: 3091857291722705477037327063091586156161
type: snfs
rlim: 134000000
alim: 134000000
lpbr: 31
lpba: 31
mfbr: 62
mfba: 62
rlambda: 2.6
alambda: 2.6[/CODE]

Test sieving 5K blocks.
[CODE] Q Yield
20M 29018
60M 21919
100M 20312[/CODE]