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Old 2019-10-16, 13:40   #1
EdH
 
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"Ed Hall"
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Default Is an SNFS Polynomial Failure of Interest?

In trying to use YAFU to obtain a polynomial for HCN 9-2,309, I received:
Code:
nfs: no snfs polynomial with small coefficients found
nfs: failed to find snfs polynomial!
phi gave me:
Code:
$ ./phi-c -deg6 309 9 2 3534129792235741914408306621791532098793213427294684124454335539028694097035564463159508064866536031250833678749571621610483094280283720170283823020320287977251682034917231068012076652908691393
n: 3534129792235741914408306621791532098793213427294684124454335539028694097035564463159508064866536031250833678749571621610483094280283720170283823020320287977251682034917231068012076652908691393
# 9^309-2^309, difficulty: 196.57, skewness: 0.61, alpha: 0.00
# cost: 1.04481e+17, est. time: 49.75 GHz days (not accurate yet!)
skew: 0.606
c6: 81
c3: 18
c0: 4
Y1: -17179869184
Y0: 278128389443693511257285776231761
m: 1753159349463657617364526571527813780702798589517014407567304614753472590106455083202112158530290625957083676520059809313632662904308203957105022808177136433567340228280492937606639194671086335
type: snfs
Full YAFU run:
Code:
$ ./yafu "snfs(9^309-2^309,3534129792235741914408306621791532098793213427294684124454335539028694097035564463159508064866536031250833678749571621610483094280283720170283823020320287977251682034917231068012076652908691393)" -v -np


10/16/19 09:12:49 v1.35-beta @ localhost.localdomain, System/Build Info: 
Using GMP-ECM 7.0.3, Powered by GMP 6.1.1
detected Intel(R) Core(TM)2 Quad CPU    Q6600  @ 2.40GHz
detected L1 = 32768 bytes, L2 = 4194304 bytes, CL = 64 bytes
measured cpu frequency ~= 2394.029340
using 1 random witnesses for Rabin-Miller 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 - no job file found
nfs: checking for poly file - no poly file found
nfs: commencing nfs on c295: 7259979873896940867568847020260885232167941558828579586657722111514940335971041788558512367317147469900539963372315484718555121318852064706620751377181611738245550630122179187889874712077711473443774742292519881496470222373488868773103452141696933797711686726450188106099771528221929947537511977
nfs: searching for brent special forms...
nfs: searching for homogeneous cunningham special forms...
nfs: input divides 9^309 - 2^309
nfs: degree 4 difficulty = 196.57, degree 6 difficulty = 196.57
nfs: choosing degree 6
Error: M=1753159349463657617364526571527813780702798589517014407567304614753472590106455083202112158530290625957083676520059809313632662904308203957105022808177136433567340228280492937606639194671086335 is not a root of f(x) % N
n = 3534129792235741914408306621791532098793213427294684124454335539028694097035564463159508064866536031250833678749571621610483094280283720170283823020320287977251682034917231068012076652908691393
f(x) = + 81*x^6 + 0*x^5 + 0*x^4 + 18*x^3 + 0*x^2 + 0*x^1 + 1*x^0 
Remainder is 3534129792235741914408306621791532098793213427294684124454335539028694097035564463159508064866536031250833678749571621610483094280283720170283823020320287977251682034917231068012076652908691390

nfs: no snfs polynomial with small coefficients found
nfs: failed to find snfs polynomial!
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Old 2019-10-16, 13:58   #2
bsquared
 
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Yes, it is of interest. Thanks!
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Old 2019-10-16, 16:04   #3
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Fix checked into yafu-wip r379.
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Old 2019-10-16, 17:45   #4
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Quote:
Originally Posted by bsquared View Post
Fix checked into yafu-wip r379.
Although I am running earlier wip versions on many of my machines, I'm no longer able to compile the wip branch of YAFU. I've assumed it is my ancient systems not keeping up with the times.

One thing I've noticed and tried editing is the gcc-7 definition, whereas mine is gcc-5. . .
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Old 2019-10-16, 17:52   #5
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It only needs gcc7 or better if you are trying to compile with avx512 support (I think). What errors do you get if you just use your gcc and don't specify USE_AVX2=1 or SKYLAKEX=1 ?
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Old 2019-10-16, 19:01   #6
EdH
 
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Quote:
Originally Posted by bsquared View Post
It only needs gcc7 or better if you are trying to compile with avx512 support (I think). What errors do you get if you just use your gcc and don't specify USE_AVX2=1 or SKYLAKEX=1 ?
Code:
$ make NFS=1 USE_SSE41=1
cc -g -DUSE_SSE41 -m64 -msse4.1 -DUSE_NFS -O3 -fomit-frame-pointer -Wall  -I. -Iinclude -Itop/aprcl -Itop/ -I../msieve/zlib -I../gmp/include -I../gmp-ecm/include/ -c -o factor/qs/msieve/lanczos.o factor/qs/msieve/lanczos.c
In file included from factor/qs/msieve/lanczos.c:20:0:
include/qs.h:30:25: fatal error: cofactorize.h: No such file or directory
 #include "cofactorize.h"
                         ^
compilation terminated.
Makefile:369: recipe for target 'factor/qs/msieve/lanczos.o' failed
make: *** [factor/qs/msieve/lanczos.o] Error 1
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Old 2019-10-16, 19:14   #7
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Update:

By copying cofactorize.h into the include directory all appears fine.** Probably not the preferred method. . .


** Including the HCN 9-2,309.


Thanks much!

Last fiddled with by EdH on 2019-10-16 at 19:21
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Old 2019-10-16, 19:31   #8
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No, that's perfect, that's where it should be. I just didn't realize that I hadn't registered that move with SVN. Glad all is well now.
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