YAFU 2.0 - Page 24

BudgieJane · 2021-09-19, 05:48

I've just run version 2.07 on my Win-7 machine, and I'm pleased to say that the trouble I was having with 2.06 does not happen with 2.07.

Code:

JANELT3 C:\Users\Jane\Documents\Maths\yafu\Versions\yafu-2.07 > yafu-x64


YAFU Version 2.07
Built with Microsoft Visual Studio 1928
Using GMP-ECM 7.0.4, Powered by MPIR 3.0.0
Detected Intel(R) Core(TM) i7-4710MQ CPU @ 2.50GHz
Detected L1 = 32768 bytes, L2 = 6291456 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) =======
=======             bbuhrow@gmail.com                   =======
=======     Type help at any time, or quit to quit      =======
===============================================================

>> nfs(296461670302265261661404037493475256820003211696331293471947264729761541)


starting SIQS on c72: 296461670302265261661404037493475256820003211696331293471947264729761541

==== sieving in progress (  4 threads):   17568 relations needed ====
====             Press ctrl-c to abort and save state            ====
17744 rels found: 6988 full + 10756 from 123762 partial, (2492.55 rels/sec)

SIQS elapsed time = 53.9072 seconds.


***factors found***

P31 = 5080439387107487549436920600141
P41 = 58353549312012091454346752496532032405401

ans = 1

>> exit

So you have yet another satisfied customer

Quote:

Originally Posted by BudgieJane

I'm having problems with version 2.06. It works OK on my new computer, running Windows 10 Pro, but it will not run on my old ones running Windows 7 Pro. It puts up the welcome message, waits something like half a minute, then quietly returns me to the command prompt:

Code:

JANELT3 C:\Users\Jane\Documents\Maths\yafu\Versions\yafu-2.06 > yafu-x64


YAFU Version 2.06
Built with Microsoft Visual Studio 1922
Using GMP-ECM 7.0.4, Powered by MPIR 3.0.0
Detected Intel(R) Core(TM) i7-4710MQ CPU @ 2.50GHz
Detected L1 = 32768 bytes, L2 = 6291456 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) =======
=======             bbuhrow@gmail.com                   =======
=======     Type help at any time, or quit to quit      =======
===============================================================

>>
JANELT3 C:\Users\Jane\Documents\Maths\yafu\Versions\yafu-2.06 >

Is there something I ought to have somewhere on those old computers but which is missing, but the new computer does have it?

James Heinrich · 2021-09-19, 12:42

Quote:

Originally Posted by James Heinrich

is it possible to add in some kind of rough ETA to SIQS

NFS is even more opaque (to those like me who don't really understand what it's doing). It outputs a lot of stuff to the screen, such as

Quote:

35916 78129054809 1418312659029451279522
hashtable: 1024 entries, 0.02 MB
total yield: 60665, q=1850021 (0.01060 sec/rel)
nfs: commencing algebraic side lattice sieving over range: 1883341 - 1890008
Warning: lowering FB_bound to 1856672.

Is it possible to provide any kind of occasional screen output that gives some kind of guidance as to where we are in the NFS progress? At least with SIQS even if there's no ETA you can get some sense of progress, but with NFS it just seems (to me) that it's not-done until it is done.

EdH · 2021-09-20, 15:11

Well, I spoke too quickly about all being well. (That should teach me a lesson, but probably won't.)

First, all my AMD machines are failing when they they try to use snfs to solve. I've temporarily sidestepped that trouble by using "snfs_xover=95." ~~I've provided more detail below.~~ I'll address this in a separate post, since the second issue is rather lengthy and I'd like to see if I can determine whether this is a YAFU or Msieve issue.

Second, I'm still having the looping issues with SIQS. At present, I have been logging a single episode with v v v and have a log file that's over 25MB. (It's been looping for nearly 11 hours.) I've also discovered that YAFU is currently using 22GB of RAM, and growing into swap. I've tried to trim the log down to the repeating section to make it fit a code block. Here is a portion of the "top" display:

Code:

Tasks: 433 total,   3 running, 430 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.5 us,  0.3 sy,  0.2 ni, 92.8 id,  6.1 wa,  0.0 hi,  0.0 si,  0.0 st
MiB Mem :  24041.0 total,    324.9 free,  23343.9 used,    372.2 buff/cache
MiB Swap:  16373.0 total,   9720.1 free,   6652.9 used.    308.1 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND  
2911573 math98    20   0   30.3g  22.0g   1212 R   7.0  93.5 627:21.54 yafu

Here's the session log:

Code:

09/20/21 00:18:25, =====================================
09/20/21 00:18:25, System/Build Info: 
09/20/21 00:18:25, YAFU Version 2.07
09/20/21 00:18:25, Built with GCC 9
09/20/21 00:18:25, Using GMP-ECM 7.0.5-dev, Powered by GMP 6.2.1
09/20/21 00:18:25, detected Intel(R) Xeon(R) CPU           X5650  @ 2.67GHz
detected L1 = 32768 bytes, L2 = 12582912 bytes, CL = 64 bytes
09/20/21 00:18:25, using 1 random witness for Rabin-Miller PRP checks
09/20/21 00:18:25, Cached 664579 primes: max prime is 9999991

09/20/21 00:18:25, Random seed: 13035443370557393521

Here's the repeating section:

Code:

found 72442 cycles from 160635 relations in 5 passes
distribution of cycle lengths:
   length 1 : 23003
   length 2 : 16947
   length 3 : 13162
   length 4 : 8489
   length 5 : 5159
   length 6 : 2853
   length 7 : 1460
   length 9+: 1369
largest cycle: 17 relations
matrix is 68528 x 72442 (16.8 MB) with weight 3819360 (52.72/col)
sparse part has weight 3819360 (52.72/col)
filtering completed in 4 passes
matrix is 59776 x 59840 (13.3 MB) with weight 3016591 (50.41/col)
sparse part has weight 3016591 (50.41/col)
saving the first 48 matrix rows for later
matrix is 59728 x 59840 (11.4 MB) with weight 2594461 (43.36/col)
sparse part has weight 2394272 (40.01/col)
matrix includes 64 packed rows
using block size 23936 for processor cache size 12288 kB
commencing Lanczos iteration
memory use: 9.4 MB
lanczos halted after 945 iterations (dim = 59721)
recovered 14 nontrivial dependencies
Lanczos elapsed time = 14.0724 seconds.
Sqrt elapsed time = 1.0826 seconds.
SIQS elapsed time = 15.7047 seconds.
pretesting / qs ratio was 1.05
fac: setting target pretesting digits to 27.38
    t15: 73.14
    t20: 33.35
    t25: 4.59
    t30: 0.48
    t35: 0.04
fac: estimated sum of completed work is t27.39

starting SIQS on c89: 11539488294330117240202826559598428302679556688248012471560145814831982545559910259149337
input from file = 11539488294330117240202826559598428302679556688248012471560145814831982545559910259149337
input to yafu = 11539488294330117240202826559598428302679556688248012471560145814831982545559910259149337
input matches with multiple of 1
static memory usage:
    initial cycle hashtable: 16777216 bytes
    initial cycle table: 160000 bytes
    factor base: 1370560 bytes
fb bounds
    small: 1024
    SPV: 38
    10bit: 104
    11bit: 176
    12bit: 312
    13bit: 552
    32k div 3: 712
    14bit: 1000
    15bit: 1760
    med: 2880
    large: 16688
    large_x2: 68528
    all: 68528
start primes
    SPV: 251
    10bit: 1063
    11bit: 2053
    12bit: 4231
    13bit: 8221
    32k div 3: 11087
    14bit: 16421
    15bit: 32803
    med: 57667
    large: 392957
    large_x2: 1823713
    all: 1823713
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
memory usage during sieving:
    curr_poly structure: 1048656 bytes
    relation buffer: 7602176 bytes
    factor bases: 184320 bytes
    update data: 890864 bytes
    sieve: 32768 bytes
    bucket data: 1573672 bytes
restarting siqs from saved data set
72443 relations found: 23003 full + 49440 from 882638 partial
threw away 0 relations with large primes too small

==== sieve params ====
n = 91 digits, 300 bits
factor base: 68528 primes (max prime = 1823713)
single large prime cutoff: 200608430 (110 * pmax)
double large prime range from 3325929106369 to 2287420354104121
DLP MFB = 1.85
using SSE2 enabled 32k sieve core
sieve interval: 12 blocks of size 32768
polynomial A has ~ 11 factors
using multiplier of 137
using Q2(x) polynomials for kN mod 8 = 1
using SPV correction of 22 bits, starting at offset 38
trial factoring cutoff at 94 bits

==== sieving in progress ( 24 threads):   68592 relations needed ====
====             Press ctrl-c to abort and save state            ====
72443 rels found: 23003 full + 49440 from 882638 partial, (1709269.38 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1709166.16 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1709121.00 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1709075.85 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1709050.04 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1709027.47 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1709001.67 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708979.09 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708953.29 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708930.72 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708904.92 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708879.13 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708856.56 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708830.76 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708808.19 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708782.40 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708692.12 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708663.11 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708640.55 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708614.76 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708592.19 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708566.40 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708543.84 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1708521.28 rels/sec)
72443 rels found: 23003 full + 49440 from 882638 partial, (1677482.63 rels/sec)

sieving required 0 total polynomials (4294967295 'A' polynomials)
trial division touched 0 sieve locations out of 0
dlp-ecm: 0 failures, 0 attempts, 0 outside range, 0 prp, 0 useful
total reports = 0, total surviving reports = 0
total blocks sieved = 0, avg surviving reports per block = -nan
Elapsed time: 0.5399 sec
QS elapsed time = 0.5400 seconds.

==== post processing stage (msieve-1.38) ====
read 905640 relations
begin singleton removal with 905640 relations
reduce to 160635 relations in 11 passes
attempting to read and process 160635 relations
recovered 160635 relations
recovered 127168 polynomials
 attempting to build 72442 cycles

I've attached a full example in text form, that has all the >2k repetitions removed.

Thanks for any help.

bsquared · 2021-09-20, 15:30

What is the command line that starts these looping jobs? I see it is a batchfile job but yafu calls pipes and redirects batchfile jobs also, I think. Wanted to see if I can duplicate here and how yafu is called may matter...

As for your difficulties with older machines I can nearly guarantee it is a yafu issue and not msieve. yafu's siqs is nearly 100% assembly or intrinsics code using sse4.1 or better. The Phenom II x4 doesn't have sse4.1. Yafu's sse2-only compile option will apparently still compile but I haven't tested that build in... a while.

Quote:

Originally Posted by BudgieJane

I've just run version 2.07 on my Win-7 machine, and I'm pleased to say that the trouble I was having with 2.06 does not happen with 2.07.

Yay, glad to hear it!

EdH · 2021-09-20, 15:35

I've also noticed that siqs.dat has a current size of over 50MB. I removed it and YAFU broke out of the loop. I've attached the end of the log, since it is too large for a code block. I have saved the larger siqs.dat, but it's too large to post. If you would like, I can work with it in some manner, or maybe compress and post it somewhere.

Thanks!

EdH · 2021-09-20, 16:06

Quote:

Originally Posted by bsquared

What is the command line that starts these looping jobs? I see it is a batchfile job but yafu calls pipes and redirects batchfile jobs also, I think. Wanted to see if I can duplicate here and how yafu is called may matter...

As for your difficulties with older machines I can nearly guarantee it is a yafu issue and not msieve. yafu's siqs is nearly 100% assembly or intrinsics code using sse4.1 or better. The Phenom II x4 doesn't have sse4.1. Yafu's sse2-only compile option will apparently still compile but I haven't tested that build in... a while.
. . .

I suspected the missing SSE4_1 was the issue. I tried building without the NFS=1 and it errorred with "nfs" references. To my untrained eye, SIQS appears to be fine. The error appears if YAFU finds the composite to be snfs compatible. Is it still running SIQS for snfs worthy composites? I'll try the sse2-only in a little while. This is a very minor issue for me, if any. The current work-around is fine.

The looping is very intermittent as a whole, so I don't think you'll be able to duplicate it easily. (That's why I have all my machines using "v v v" to a log file.) Last night, I factored several thousand composites in the 89 digit range across several machines and only one looped. (Unfortunately, it takes that machine out of the system until I intervene.) The previous night, during about the same time frame, four looped. YAFU is being called via a BASH script line:

Code:

echo "factor(${composite})" | ./yafu -one >>dbW.log

(The "-one" might be working now, but I haven't verified.)

The siqs.dat file is explicitly deleted prior to each run and the dbW.log file is re-initialized for each run as well, so they are purely written by the current iteration of YAFU.

Thanks for all.

bsquared · 2021-09-20, 16:15

Quote:

Originally Posted by EdH

I suspected the missing SSE4_1 was the issue. I tried building without the NFS=1 and it errorred with "nfs" references. To my untrained eye, SIQS appears to be fine. The error appears if YAFU finds the composite to be snfs compatible. Is it still running SIQS for snfs worthy composites? I'll try the sse2-only in a little while. This is a very minor issue for me, if any. The current work-around is fine.

Ok I guess I misunderstood; I thought it was a siqs issue not snfs. If I read fast those two acronyms look the same

So ignore everything I said about sse2/4.1, that shouldn't be an issue with snfs. For snfs the yafu-side code should be pretty agnostic to cpu... so I'm not sure why it would not work with older machines. Maybe it's an msieve issue after all. I will take a look at the yafu side at least and see if anything occurs to me.

Plutie · 2021-09-20, 18:30

A couple feature requests/thoughts:
Would it be possible to implement aurifeuillian factor calculation? would speed up factorization of certain forms.
Would prioritizing composite factors found via rho/ecm be a feature you'd be able to add?

EdH · 2021-09-21, 18:24

So far today I've found four instances (includes overnight). But, again, that's in several thousand factorizations, so it's still not common.

I found some interesting (at least to me) bits in factor.log of one of the machines. I've attached the whole log.

Of interest, I found these differences between failed loops and the final one that was after I removed siqs.dat.

Here are some lines from the failed loop just previous to the successful one:

Code:

09/21/21 12:33:35, DLP MFB = 1.85
09/21/21 12:33:35, using SSE41 enabled 32k sieve core
09/21/21 12:33:35, sieve interval: 13 blocks of size 32768
09/21/21 12:33:35, polynomial A has ~ 12 factors
. . .
09/21/21 12:33:35, ==== sieving started ( 8 threads) ====
09/21/21 12:33:35, trial division touched 0 sieve locations out of 0
09/21/21 12:33:35, total reports = 0, total surviving reports = 0
09/21/21 12:33:35, total blocks sieved = 0, avg surviving reports per block = -nan
09/21/21 12:33:35, dlp-ecm: 0 failures, 0 attempts, 0 outside range, 0 prp, 0 useful
09/21/21 12:33:35, 79066 relations found: 21666 full + 57400 from 1145924 partial, using 0 polys (-1 A polys)
09/21/21 12:33:35, on average, sieving found inf rels/poly and 2083055.32 rels/sec
09/21/21 12:33:35, trial division touched 0 sieve locations out of 0
09/21/21 12:33:35, ==== post processing stage (msieve-1.38) ====
 09/21/21 12:33:35, QS elapsed time = 0.5606 seconds.
. . .
09/21/21 12:33:52, lanczos halted after 1138 iterations (dim = 71861)
09/21/21 12:33:52, recovered 15 nontrivial dependencies
09/21/21 12:33:54, Lanczos elapsed time = 17.6298 seconds.
09/21/21 12:33:54, Sqrt elapsed time = 1.2765 seconds.
09/21/21 12:33:54, SIQS elapsed time = 19.4675 seconds.

and, here are corresponding sections of the successful completion:

Code:

09/21/21 12:33:54, DLP MFB = 1.85
 09/21/21 12:33:54, allocating 8 large prime slices of factor base
09/21/21 12:33:54, buckets hold 2048 elements
09/21/21 12:33:54, large prime hashtables have 1703936 bytes
09/21/21 12:33:54, using SSE41 enabled 32k sieve core
09/21/21 12:33:54, sieve interval: 13 blocks of size 32768
09/21/21 12:33:54, polynomial A has ~ 12 factors
. . .
09/21/21 12:33:54, ==== sieving started ( 8 threads) ====
09/21/21 12:38:46, trial division touched 39333795 sieve locations out of 521638707200
09/21/21 12:38:46, total reports = 39333795, total surviving reports = 13059246
09/21/21 12:38:46, total blocks sieved = 15919150, avg surviving reports per block = 0.82
09/21/21 12:38:46, dlp-ecm: 25 failures, 1061012 attempts, 7063329 outside range, 4629850 prp, 860162 useful
09/21/21 12:38:46, 78670 relations found: 21569 full + 57101 from 1143648 partial, using 612275 polys (1100 A polys)
09/21/21 12:38:46, on average, sieving found 1.90 rels/poly and 3985.64 rels/sec
09/21/21 12:38:46, trial division touched 39333795 sieve locations out of 521638707200
09/21/21 12:38:46, ==== post processing stage (msieve-1.38) ====
09/21/21 12:38:46, QS elapsed time = 292.3540 seconds.
. . .
09/21/21 12:39:03, lanczos halted after 1139 iterations (dim = 71926)
09/21/21 12:39:03, recovered 16 nontrivial dependencies
09/21/21 12:39:04, prp59 = 52849932024287778885817430875314364339557493580386262089853
09/21/21 12:39:04, prp33 = 166873661278274944173735579427313
09/21/21 12:39:04, Lanczos elapsed time = 17.4163 seconds.
09/21/21 12:39:04, Sqrt elapsed time = 0.3407 seconds.
09/21/21 12:39:04, SIQS elapsed time = 310.1780 seconds.

There are, of course other differences, as can be seen in factor.log. Hopefully, this info is helpful.

Thanks for all.

bsquared · 2021-09-21, 19:41

Quote:

Originally Posted by EdH

So far today I've found four instances (includes overnight). But, again, that's in several thousand factorizations, so it's still not common.

The differences in those bits of log stem from the fact that the first one was a restart and the second one wasn't. But why would the first one restart after everything apparently completed? The only thing I can think of is that no factor was found in the 15 dependencies. In that case yafu would try to redo the factorization, but since a data file still exists it would of course just reuse it, and the same 0-for-15 result would ensue during the sqrt phase. And so on.

When you manually delete the file then a different set of dependencies would result and (with high likelihood) the factorization completes successfully.

Assuming this conclusion is correct, the question now is what to do about it. First, detect it, and second, probably do some more sieving. Maybe step zero is to just print some statement to the log file that no factors were found during sqrt. Then your script can see it and start over.

EdH · 2021-09-21, 19:58

Could I delete siqs.dat as soon as "SIQS elapsed time" appears in factor.log? Is there any need for siqs.dat to exist after that point? It would be easy for me to have a separate script watching factor.log for that line and invoke a deletion. As long as that wouldn't interfere with normal runs, I'll try it. I'm already deleting siqs.dat prior to each run anyway. This would just do it sooner.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
yafu ignoring yafu.ini	chris2be8	YAFU	9	2022-02-17 17:52
Running YAFU via Aliqueit doesn't find yafu.ini	EdH	YAFU	8	2018-03-14 17:22
YAFU-1.34	bsquared	YAFU	119	2015-11-05 16:24
Yafu bug.	storflyt32	YAFU	2	2015-06-29 05:19
yafu 1.32	bsquared	YAFU	28	2012-07-20 16:17

2021-09-20, 18:30	#261
Plutie "Evan" Dec 2020 Montreal 1001000₂ Posts	A couple feature requests/thoughts: Would it be possible to implement aurifeuillian factor calculation? would speed up factorization of certain forms. Would prioritizing composite factors found via rho/ecm be a feature you'd be able to add?

2021-09-21, 19:58	#264
EdH "Ed Hall" Dec 2009 Adirondack Mtns 3³×167 Posts	Could I delete siqs.dat as soon as "SIQS elapsed time" appears in factor.log? Is there any need for siqs.dat to exist after that point? It would be easy for me to have a separate script watching factor.log for that line and invoke a deletion. As long as that wouldn't interfere with normal runs, I'll try it. I'm already deleting siqs.dat prior to each run anyway. This would just do it sooner.