20091230, 14:12  #1 
"Ben"
Feb 2007
3,371 Posts 
square root crash
I'm getting a segmentation fault during the square root phase. It has been repeatable for at least one dependency; I'm trying other dependencies now.
This occurred during factorization of aliquot sequence 4788 at iteration 2503, on a c137. I still have all the data, matrix, and dependency files. Code:
Msieve v. 1.44 Wed Dec 30 07:54:27 2009 random seeds: 924ede45 75091bcc factoring 40749881176591001313668881738461183359103092070283580604476483864940722559707999223166066411471564908270442953165453791845420594628304571 (137 digits) searching for 15digit factors commencing number field sieve (137digit input) R0: 186181968602879312631151995 R1: 2753343120517687 A0: 75928063558542655529864860597168 A1: 9182525920185050132113778204 A2: 16139511119661987272384 A3: 39176187555574241 A4: 418654113212 A5: 182160 skew 1.00, size 3.030638e13, alpha 7.007098, combined = 6.732510e13 commencing square root phase reading relations for dependency 1 read 876854 cycles cycles contain 2615106 unique relations read 2615106 relations multiplying 2615106 relations Segmentation fault 
20091230, 14:18  #2 
Tribal Bullet
Oct 2004
2·3·19·31 Posts 
If on a linux system, can you rebuild with 'make x86_64 OPT_FLAGS=g', then
PM me the output of 'bt full' from gdb after the segfault occurs in the debug binary? I hope building the debug code will be sufficient, otherwise you can mail me a DVD :) 
20091230, 14:19  #3 
"Ben"
Feb 2007
3,371 Posts 
Dependency 2 has also just failed in the same way. I'll try a previous version of msieve...
I'll build the debug binary as well. Interestingly, a previous version finds more unique relations in the first dependency, but multiplies the same number together in the end... and also works! Code:
Msieve v. 1.42 Wed Dec 30 08:22:32 2009 random seeds: 749a61a9 ff6d6c87 factoring 40749881176591001313668881738461183359103092070283580604476483864940722559707999223166066411471564908270442953165453791845420594628304571 (137 digits) no P1/P+1/ECM available, skipping commencing number field sieve (137digit input) R0: 186181968602879312631151995 R1: 2753343120517687 A0: 75928063558542655529864860597168 A1: 9182525920185050132113778204 A2: 16139511119661987272384 A3: 39176187555574241 A4: 418654113212 A5: 182160 skew 1.00, size 3.030638e13, alpha 7.007098, combined = 6.732510e13 commencing square root phase reading relations for dependency 1 read 876854 cycles cycles contain 3228004 unique relations read 3228004 relations multiplying 2615106 relations multiply complete, coefficients have about 132.56 million bits initial square root is modulo 57221 sqrtTime: 856 prp60 factor: 345904004092746503021088299379972074287902300978671971758577 prp78 factor: 117806907969948860631659379351218221407555470977030568931916016398691505794923 elapsed time 00:14:17 Last fiddled with by bsquared on 20091230 at 14:37 Reason: more info 
20091230, 15:03  #4 
Oct 2004
Austria
2×17×73 Posts 

20091230, 16:36  #5 
"Ben"
Feb 2007
3,371 Posts 
I'm not sure how the msieve version sync's with the SVN version. 1.44 is what I got when I built the trunk code about a month ago...

20091230, 17:14  #6  
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
2×41×71 Posts 
Quote:
since 1.44 is not yet released that means we are dealing with an svn version 

20100408, 15:32  #7 
Mar 2010
33_{16} Posts 
So I did post this in another thread before I saw this one.
I am getting a seg fault using msieve 1.45 from svn. Is it necessary to use a previous version of msieve for the square root part? Code:
commencing square root phase reading relations for dependency 1 read 2090616 cycles cycles contain 5829738 unique relations read 5829738 relations multiplying 5829738 relations Segmentation fault 
20100408, 16:36  #8 
"Ben"
Feb 2007
3,371 Posts 
Save the data! As far as I know Jason is still working on a fix for this, and he may need/want the .mat, .dep and other files...

20100408, 16:59  #9 
(loop (#_fork))
Feb 2006
Cambridge, England
2·3,191 Posts 
I'm getting the same.
svn update (to revision 239), rebuilt, rerun under gdb, and Code:
(gdb) bt #0 0x00002b7d375fa67d in __gmpz_add_ui () from /usr/lib64/libgmp.so.3 #1 0x00000000004238ea in gmp_poly_mul (p1=0x7fff735d5260, p2=<value optimized out>, mod=0x7fff735d6040, free_p2=1) at gnfs/sqrt/sqrt_a.c:191 #2 0x0000000000423d2f in multiply_relations (prodinfo=0x7fff735d6360, index1=0, index2=2238503, prod=0x7fff735d5f20) at gnfs/sqrt/sqrt_a.c:368 #3 0x0000000000424365 in alg_square_root (obj=0x565250, mp_alg_poly=0x7fff735d7270, n=0x7fff735d9120, c=0x7fff735d7a80, m1=0x7fff735d6504, m0=0x7fff735d6484, rlist=0x2b7d37bc1010, num_relations=2238504, check_q=2147483693, sqrt_a=0x7fff735d7b00) at gnfs/sqrt/sqrt_a.c:692 #4 0x0000000000423070 in nfs_find_factors (obj=0x565250, n=0x7fff735d9120, factor_list=0x7fff735d8810) at gnfs/sqrt/sqrt.c:407 #5 0x000000000041535f in factor_gnfs (obj=0x565250, n=0x7fff735d9120, factor_list=0x7fff735d8810) at gnfs/gnfs.c:160 #6 0x0000000000404a17 in msieve_run (obj=0x565250) at common/driver.c:151 #7 0x0000000000402e8e in factor_integer ( buf=0x7fff735d9480 "33577312629044687322683253176370859946062994512713093161690045173177708208628447962919655873151495194809846780665350950840026037372937", flags=1027, savefile_name=0x0, logfile_name=0x0, nfs_fbfile_name=0x0, seed1=0x7fff735d963c, seed2=0x7fff735d9638, max_relations=0, nfs_lower=0, nfs_upper=0, cpu=cpu_opteron, cache_size1=65536, cache_size2=1048576, num_threads=0, mem_mb=0, which_gpu=0) at demo.c:186 #8 0x0000000000403974 in main (argc=3, argv=0x7fff735d9758) at demo.c:525 Code:
190 for (j = d1; j; j) { 191 mpz_addmul(tmp[j], p1>coeff[j], p2>coeff[i]); 192 } This is compilerdependent: the build on an opteron machine with gcc4.1.0 fails, a build on a core2 machine with gcc4.3.2 and exactly the same makefile works. 
20100408, 17:30  #10  
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
24544_{8} Posts 
Quote:
I've been unable to get a usable build on any Unixlike system. The workaround in my case is to run the square root phase on a (virtual) WinXP machine. Paul 

20100408, 18:46  #11  
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
3^{2}×17×61 Posts 
Quote:
With gcc4.3.2, I haven't seen any sqrt problems. Possibly related: I have seen weird subtle bugs on 16e sievers built with gcc4.1.2 and not with gcc4.3.2. 

Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
All square roots failed  chris2be8  Msieve  13  20201014 07:08 
Square Root Days  davar55  Lounge  0  20160316 20:19 
NFS Square root problems  paul0  Factoring  10  20150119 12:25 
Square root of 3  Damian  Math  3  20100101 01:56 
Divisible up to Square Root  davar55  Puzzles  3  20070905 15:59 