YAFU 2.0

[richs]

Originally Posted by bsquared

Thanks for the report. This is due to the same bug Stargate reported and will be fixed after I'm able to re-build the project tonight.

Thanks! I'll get the revised executable when available.

[BudgieJane]

I've just managed to factor a C190 into PRP26, PRP52 and PRP113 using YAFU 2.02. It took 5 days and 5 hours, but that's down to my awful hardware. I am pleased with this.

If anyone's interested the C190 was 30^128 + 17^128.

Incidentally, I'm sure I've seen something posted about this here before, but what's the largest number of decimal digits YAFU will handle?

[Stargate38]

I've run partial factorizations of larger numbers (up to 900 digits; sometimes Yafu will crash on numbers >1000 digits, but that was before I upgraded to 2.x), and sometimes I'll get a full factorization, but it's very rare.

Any chance you could post the factors of 30^128+17^128 on FactorDB? It still says it's a C190: http://www.factordb.com/index.php?id...00000441930677

[BudgieJane]

Originally Posted by Stargate38

I've run partial factorizations of larger numbers (up to 900 digits; sometimes Yafu will crash on numbers >1000 digits, but that was before I upgraded to 2.x), and sometimes I'll get a full factorization, but it's very rare.

Thank you.

Originally Posted by Stargate38

Any chance you could post the factors of 30^128+17^128 on FactorDB? It still says it's a C190: http://www.factordb.com/index.php?id...00000441930677

Done.
How many of these Homogeneous Cunninghams should go onto FactorDB? I've got a lot of them that I've not been posting after someone complained about them a few years back.

[EdH]

05/26/21 10:01:49 v1.35-beta @ math97, System/Build Info: 
Using GMP-ECM 7.0.5-dev, Powered by GMP 6.2.0
detected         Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
detected L1 = 32768 bytes, L2 = 8388608 bytes, CL = 64 bytes
measured cpu frequency ~= 3392.250200
using 1 random witnesses for Rabin-Miller PRP checks
. . .
cached 664579 primes. pmax = 9999991
 

>> sigma(28,1)
56
>>

YAFU Version 2.0
Built with GCC 9
Using GMP-ECM 7.0.5-dev, Powered by GMP 6.2.0
Detected         Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
Detected L1 = 32768 bytes, L2 = 8388608 bytes, CL = 64 bytes
Using 1 random witness for Rabin-Miller PRP checks
Cached 664579 primes; max prime is 9999991
. . .
>> sigma(28,1)

ans = 1

>>

[chris2be8]

Originally Posted by BudgieJane

How many of these Homogeneous Cunninghams should go onto FactorDB? I've got a lot of them that I've not been posting after someone complained about them a few years back.

Assuming you don't have millions of them they should all go into factordb once you have fully factored them.

I think I once complained about a load of small unfactored ones being added to factordb (I am running a script to factor small number iin factordb, it went to the trouble of factoring them only to find them done when it tried to submit the result).

Chris

[bsquared]

Version 2.03 is now available with recently reported bugs fixed. Thanks Stargate38, richs, and EdH!

[EdH]

Great! Thanks for all your work!

[richs]

Thanks, Ben. Your efforts are most appreciated!

[charybdis]

There appears to be a bug in SNFS polynomial selection for (at least) the k*b^n+-1 and b^n+-k forms, for example:

$ yafu "snfs(1281979*2^520+1,615852095139018818180740532155742854813285752039357209617222174313731523072704248288595303399267379211703243385678043310396893565702501281889421988426549324889)"
Applying tune_info entry for LINUX64 - Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz



YAFU Version 2.02
Built with GCC 9
Using GMP-ECM 7.0.5-dev, Powered by GMP 6.2.1
Detected Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz
Detected L1 = 32768 bytes, L2 = 9437184 bytes, CL = 64 bytes
Using 1 random witness for Rabin-Miller PRP checks
Cached 664579 primes; max prime is 9999991

===============================================================
======= Welcome to YAFU (Yet Another Factoring Utility) =======
=======               [email redacted]                  =======
=======     Type help at any time, or quit to quit      =======
===============================================================

>> nfs: checking for job file - no job file found
nfs: checking for poly file - no poly file found
nfs: commencing nfs on c163: 4400263219768289455901391102252782697640926698321207262715052435471611732354471854022013442787765424467619673990669619452785804526944371659099920107307694926331905
nfs: searching for brent special forms...
nfs: input divides 1281979*2^520 + 1
gen: ========================================================
gen: considering the following polynomials:
gen: ========================================================

Error: M=1361129467683753853853498429727072845824 is not a root of f(x) % N
n = 615852095139018818180740532155742854813285752039357209617222174313731523072704248288595303399267379211703243385678043310396893565702501281889421988426549324889
f(x) = + 1281979*x^4 + 0*x^3 + 0*x^2 + 0*x^1 - -1*x^0
Remainder is 615852095139018818180740532155742854813285752039357209617222174313731523072704248288595303399267379211703243385678043310396893565702501281889421988426549324887

Error: M=20282409603651670423947251286016 is not a root of f(x) % N
n = 615852095139018818180740532155742854813285752039357209617222174313731523072704248288595303399267379211703243385678043310396893565702501281889421988426549324889
f(x) = + 1281979*x^5 + 0*x^4 + 0*x^3 + 0*x^2 + 0*x^1 - -1*x^0
Remainder is 615852095139018818180740532155742854813285752039357209617222174313731523072704248288595303399267379211703243385678043310396893565702501281889421988426549324887

nfs: no snfs polynomial with small coefficients found
nfs: failed to find snfs polynomial!

Those remainders would suggest that YAFU is getting the sign of the constant term wrong. This is 2.02 but it doesn't look like anything relevant has changed in 2.03.

Also, I notice that the required ECM effort is not reduced when an SNFS special form is detected, necessitating a manual change to pretest_ratio.

[EdH]

Sorry if I'm becoming annoying, but the current "-silent" option doesn't act as before. I can (re)write my scripts around it (or use YAFU 1...), but the original YAFU performed thusly:

$ ./yafu "sigma(28,1)-28" -silent
28
$

which was easy to capture in a script.

YAFU 2... performs in this manner:

$ ./yafu "sigma(28,1)-28" -silent

ans = 28

$

Although I can parse these three lines, it is easier not having to.

Thanks for all your development work.