Reserved for MF - Sequence 4788 - Page 71

Batalov · 2010-02-09, 07:46

I'll do the c112.

Batalov · 2010-02-09, 10:27

Quote:

Originally Posted by Batalov

I'll do the c112.

Done.

P.S. i2518: c128 is ECMed enough. Time to gnfs.

jrk · 2010-02-09, 22:01

I'll start a poly selection on the c128.

jrk · 2010-02-10, 18:23

Quote:

Originally Posted by jrk

I'll start a poly selection on the c128.

Use this one:

Code:

n: 12413146892411335212475324738611103299821881025295924598543239901364996511237911261347337655057269845534039368928550681048097703
# norm 3.269894e-12 alpha -8.004251 e 1.168e-10
skew: 1072068.48
c0:  1730676659846478611597742312805725
c1:  1810479060829332238437319809
c2:  863955747933414064265
c3: -4527605540759177
c4: -3009875302
c5:  4680
Y0: -4838689711426194559472012
Y1:  48926616529223
rlim: 5000000
alim: 5000000
lpbr: 26
lpba: 26
mfbr: 52
mfba: 52
rlambda: 2.5
alambda: 2.5

Sieve with 13e from Q=2M to 7M

Andi47 · 2010-02-10, 18:37

Quote:

Originally Posted by jrk

Use this one:

Code:

n: 12413146892411335212475324738611103299821881025295924598543239901364996511237911261347337655057269845534039368928550681048097703
# norm 3.269894e-12 alpha -8.004251 e 1.168e-10
skew: 1072068.48
c0:  1730676659846478611597742312805725
c1:  1810479060829332238437319809
c2:  863955747933414064265
c3: -4527605540759177
c4: -3009875302
c5:  4680
Y0: -4838689711426194559472012
Y1:  48926616529223
rlim: 5000000
alim: 5000000
lpbr: 26
lpba: 26
mfbr: 52
mfba: 52
rlambda: 2.5
alambda: 2.5

Sieve with 13e from Q=2M to 7M

Are you sure about lpbr/a 26? afik the crossover (26/27) is around c110?

jrk · 2010-02-10, 18:59

Quote:

Originally Posted by Andi47

Are you sure about lpbr/a 26? afik the crossover (26/27) is around c110?

I checked. 26 appeared to have a slight edge.

27bit:

Code:

Warning:  lowering FB_bound to 1999999.
total yield: 2674, q=2001037 (0.01092 sec/rel)
Warning:  lowering FB_bound to 2499999.
total yield: 2654, q=2501003 (0.01143 sec/rel)
Warning:  lowering FB_bound to 2999999.
total yield: 2979, q=3001001 (0.01096 sec/rel)
Warning:  lowering FB_bound to 3499999.
total yield: 2647, q=3501041 (0.01130 sec/rel)
Warning:  lowering FB_bound to 3999999.
total yield: 3083, q=4001003 (0.01163 sec/rel)
Warning:  lowering FB_bound to 4499999.
total yield: 3528, q=4501001 (0.01186 sec/rel)
total yield: 2687, q=5001001 (0.01180 sec/rel)
total yield: 2570, q=5501003 (0.01231 sec/rel)
total yield: 2608, q=6001013 (0.01274 sec/rel)
total yield: 2772, q=6501007 (0.01297 sec/rel)

26bit:

Code:

Warning:  lowering FB_bound to 1999999.
total yield: 1458, q=2001037 (0.01964 sec/rel)
Warning:  lowering FB_bound to 2499999.
total yield: 1385, q=2501003 (0.02134 sec/rel)
Warning:  lowering FB_bound to 2999999.
total yield: 1511, q=3001001 (0.02105 sec/rel)
Warning:  lowering FB_bound to 3499999.
total yield: 1361, q=3501041 (0.02142 sec/rel)
Warning:  lowering FB_bound to 3999999.
total yield: 1554, q=4001003 (0.02247 sec/rel)
Warning:  lowering FB_bound to 4499999.
total yield: 1767, q=4501001 (0.02313 sec/rel)
total yield: 1326, q=5001001 (0.02333 sec/rel)
total yield: 1297, q=5501003 (0.02375 sec/rel)
total yield: 1297, q=6001013 (0.02500 sec/rel)
total yield: 1412, q=6501007 (0.02487 sec/rel)

Andi47 · 2010-02-10, 19:22

Quote:

Originally Posted by jrk

I checked. 26 appeared to have a slight edge.

I am quite surprised about this.

Have you checked smaller numbers than c128 (i.e. ~c112 to c125) for lpb 26 / 27? Is it always that close?

FactorEyes · 2010-02-10, 20:48

Code:

lpbr: 26
lpba: 26
mfbr: 52
mfba: 52

I have seen few people set mfbX to twice lpbX for jobs of this size, but that doesn't mean you're doing it wrong.

The belief in using 27-bit large primes for gnfs jobs starting at around 110 bits may stem from the original def-par.txt file, which doesn't always have mfbr=2*lpbr and mfba=2*lpba.

These estimates may have been influenced by the nature of hardware several years back. Or not.

Likewise, it may be smarter now to use twice the number of bits for mfbX as for lpbX, even for these smaller gnfs jobs. Or not.

As should be obvious, I have more questions than answers here. I played around with differing mfbr:lpbr and mfba:lpba ratios a while back, and the ones in def-par looked pretty good for these sizes of number, but I didn't have the smarts to try lowering lpbr & lpba.

You may be on to something.

jrk · 2010-02-10, 21:27

Quote:

Originally Posted by FactorEyes

Code:

lpbr: 26
lpba: 26
mfbr: 52
mfba: 52

I have seen few people set mfbX to twice lpbX for jobs of this size, but that doesn't mean you're doing it wrong.

The belief in using 27-bit large primes for gnfs jobs starting at around 110 bits may stem from the original def-par.txt file, which doesn't always have mfbr=2*lpbr and mfba=2*lpba.

I should mention that in the trials of 27 vs 26bit I posted above, the mfbr/a was 2x of lpbr/a in each.

But here is 27 lpbr/a with 52 mfbr/a, for comparison, again using 5M small prime limit and siever 13e:

Code:

Warning:  lowering FB_bound to 1999999.
total yield: 2516, q=2001037 (0.01147 sec/rel)
Warning:  lowering FB_bound to 2499999.
total yield: 2442, q=2501003 (0.01221 sec/rel)
Warning:  lowering FB_bound to 2999999.
total yield: 2723, q=3001001 (0.01172 sec/rel)
Warning:  lowering FB_bound to 3499999.
total yield: 2390, q=3501041 (0.01221 sec/rel)
Warning:  lowering FB_bound to 3999999.
total yield: 2792, q=4001003 (0.01256 sec/rel)
Warning:  lowering FB_bound to 4499999.
total yield: 3201, q=4501001 (0.01276 sec/rel)
total yield: 2411, q=5001001 (0.01286 sec/rel)
total yield: 2319, q=5501003 (0.01334 sec/rel)
total yield: 2355, q=6001013 (0.01381 sec/rel)
total yield: 2500, q=6501007 (0.01409 sec/rel)

27,52 is slower than either 27,54 or 26,52

So it appears that using mfbr/a of 2x of lpbr/a is good even for a number as small as c128.

Although it probably have more to do with the properties of the polynomial, rather than the number size.

For that matter I also had a polynomial of E 1.25e-10 with alpha -6.15 but it was slower by comparison to the one I posted.

Quote:

Originally Posted by Andi47

Have you checked smaller numbers than c128 (i.e. ~c112 to c125) for lpb 26 / 27? Is it always that close?

No I haven't checked.

axn · 2010-02-10, 22:22

Quote:

Originally Posted by jrk

27,52 is slower than either 27,54

Yes, but 27,52 requires fewer relations than 27,54 (something like 10%(?) less). So...

Batalov · 2010-02-10, 22:38

Quote:

Originally Posted by axn

Yes, but 27,52 requires fewer relations than 27,54 (something like 10%(?) less). So...

No, it doesn't. "52" only controls the internal mechanics of the siever. It should be chosen to optimize the speed.

Like one person was quoted saying about high-throughput screening of chemical compounds: when confronted with the question, "but your technique misses a lot of hits?" he answered "but it does that so much faster than the competitors!"

2010-02-10, 20:48	#778
FactorEyes Oct 2006 vomit_frame_pointer 2³×3²×5 Posts	Code: lpbr: 26 lpba: 26 mfbr: 52 mfba: 52 I have seen few people set mfbX to twice lpbX for jobs of this size, but that doesn't mean you're doing it wrong. The belief in using 27-bit large primes for gnfs jobs starting at around 110 bits may stem from the original def-par.txt file, which doesn't always have mfbr=2lpbr and mfba=2lpba. These estimates may have been influenced by the nature of hardware several years back. Or not. Likewise, it may be smarter now to use twice the number of bits for mfbX as for lpbX, even for these smaller gnfs jobs. Or not. As should be obvious, I have more questions than answers here. I played around with differing mfbr:lpbr and mfba:lpba ratios a while back, and the ones in def-par looked pretty good for these sizes of number, but I didn't have the smarts to try lowering lpbr & lpba. You may be on to something.

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2010-02-09, 07:46	#771
Batalov "Serge" Mar 2008 Phi(4,2^7658614+1)/2 10010100011001₂ Posts	I'll do the c112.

2010-02-09, 22:01	#773
jrk May 2008 3·5·73 Posts	I'll start a poly selection on the c128.