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 2009-01-11, 14:10 #1 Andi47     Oct 2004 Austria 2·17·73 Posts Lanczos error Just got this error when running a c107 GNFS factorization on my P4: Code: Sun Jan 11 13:30:48 2009 Msieve v. 1.39 Sun Jan 11 13:30:48 2009 random seeds: 28de8eac 2089edbe Sun Jan 11 13:30:48 2009 factoring 49522765289485889233681931153717435991979703139426318174911416089221747128358987182858892932767806807975353 (107 digits) Sun Jan 11 13:30:49 2009 searching for 15-digit factors Sun Jan 11 13:30:51 2009 commencing number field sieve (107-digit input) Sun Jan 11 13:30:51 2009 R0: -438344816114060314814 Sun Jan 11 13:30:51 2009 R1: 132924059497 Sun Jan 11 13:30:51 2009 A0: -111978409899830736166589619 Sun Jan 11 13:30:51 2009 A1: 10900893999882414321130 Sun Jan 11 13:30:51 2009 A2: -73456024489071382 Sun Jan 11 13:30:51 2009 A3: -14805200109600 Sun Jan 11 13:30:51 2009 A4: 94944591 Sun Jan 11 13:30:51 2009 A5: 3060 Sun Jan 11 13:30:51 2009 skew 36845.15, size 5.659998e-011, alpha -5.326807, combined = 3.341570e-010 Sun Jan 11 13:30:51 2009 Sun Jan 11 13:30:51 2009 commencing relation filtering Sun Jan 11 13:30:51 2009 commencing duplicate removal, pass 1 Sun Jan 11 13:31:51 2009 found 347118 hash collisions in 4712358 relations Sun Jan 11 13:32:18 2009 added 31775 free relations Sun Jan 11 13:32:19 2009 commencing duplicate removal, pass 2 Sun Jan 11 13:32:29 2009 found 324399 duplicates and 4419733 unique relations Sun Jan 11 13:32:29 2009 memory use: 43.3 MB Sun Jan 11 13:32:29 2009 reading rational ideals above 2949120 Sun Jan 11 13:32:29 2009 reading algebraic ideals above 2949120 Sun Jan 11 13:32:29 2009 commencing singleton removal, pass 1 Sun Jan 11 13:33:30 2009 relations with 0 large ideals: 110837 Sun Jan 11 13:33:30 2009 relations with 1 large ideals: 695096 Sun Jan 11 13:33:30 2009 relations with 2 large ideals: 1569426 Sun Jan 11 13:33:30 2009 relations with 3 large ideals: 1492049 Sun Jan 11 13:33:30 2009 relations with 4 large ideals: 502184 Sun Jan 11 13:33:30 2009 relations with 5 large ideals: 20134 Sun Jan 11 13:33:30 2009 relations with 6 large ideals: 30007 Sun Jan 11 13:33:30 2009 relations with 7+ large ideals: 0 Sun Jan 11 13:33:30 2009 4419733 relations and about 4338337 large ideals Sun Jan 11 13:33:30 2009 commencing singleton removal, pass 2 Sun Jan 11 13:34:31 2009 found 1969447 singletons Sun Jan 11 13:34:31 2009 current dataset: 2450286 relations and about 1970706 large ideals Sun Jan 11 13:34:31 2009 commencing singleton removal, pass 3 Sun Jan 11 13:35:07 2009 found 462026 singletons Sun Jan 11 13:35:07 2009 current dataset: 1988260 relations and about 1474077 large ideals Sun Jan 11 13:35:07 2009 commencing singleton removal, final pass Sun Jan 11 13:35:39 2009 memory use: 37.3 MB Sun Jan 11 13:35:39 2009 commencing in-memory singleton removal Sun Jan 11 13:35:39 2009 begin with 1988260 relations and 1515227 unique ideals Sun Jan 11 13:35:41 2009 reduce to 1664707 relations and 1182437 ideals in 16 passes Sun Jan 11 13:35:41 2009 max relations containing the same ideal: 47 Sun Jan 11 13:35:42 2009 reading rational ideals above 720000 Sun Jan 11 13:35:42 2009 reading algebraic ideals above 720000 Sun Jan 11 13:35:42 2009 commencing singleton removal, final pass Sun Jan 11 13:36:12 2009 keeping 1467428 ideals with weight <= 20, new excess is 187057 Sun Jan 11 13:36:13 2009 memory use: 46.9 MB Sun Jan 11 13:36:13 2009 commencing in-memory singleton removal Sun Jan 11 13:36:14 2009 begin with 1672568 relations and 1467428 unique ideals Sun Jan 11 13:36:17 2009 reduce to 1651369 relations and 1408316 ideals in 15 passes Sun Jan 11 13:36:17 2009 max relations containing the same ideal: 20 Sun Jan 11 13:36:18 2009 removing 139447 relations and 126414 ideals in 13033 cliques Sun Jan 11 13:36:18 2009 commencing in-memory singleton removal Sun Jan 11 13:36:18 2009 begin with 1511922 relations and 1408316 unique ideals Sun Jan 11 13:36:20 2009 reduce to 1503837 relations and 1273735 ideals in 8 passes Sun Jan 11 13:36:20 2009 max relations containing the same ideal: 20 Sun Jan 11 13:36:21 2009 removing 101981 relations and 88948 ideals in 13033 cliques Sun Jan 11 13:36:21 2009 commencing in-memory singleton removal Sun Jan 11 13:36:21 2009 begin with 1401856 relations and 1273735 unique ideals Sun Jan 11 13:36:22 2009 reduce to 1396557 relations and 1179452 ideals in 7 passes Sun Jan 11 13:36:22 2009 max relations containing the same ideal: 20 Sun Jan 11 13:36:23 2009 relations with 0 large ideals: 15119 Sun Jan 11 13:36:23 2009 relations with 1 large ideals: 105699 Sun Jan 11 13:36:23 2009 relations with 2 large ideals: 301464 Sun Jan 11 13:36:23 2009 relations with 3 large ideals: 437317 Sun Jan 11 13:36:23 2009 relations with 4 large ideals: 344432 Sun Jan 11 13:36:23 2009 relations with 5 large ideals: 148754 Sun Jan 11 13:36:23 2009 relations with 6 large ideals: 38263 Sun Jan 11 13:36:23 2009 relations with 7+ large ideals: 5509 Sun Jan 11 13:36:23 2009 commencing 2-way merge Sun Jan 11 13:36:25 2009 reduce to 826083 relation sets and 608978 unique ideals Sun Jan 11 13:36:25 2009 commencing full merge Sun Jan 11 13:36:37 2009 memory use: 46.5 MB Sun Jan 11 13:36:37 2009 found 385635 cycles, need 359178 Sun Jan 11 13:36:37 2009 weight of 359178 cycles is about 25497695 (70.99/cycle) Sun Jan 11 13:36:37 2009 distribution of cycle lengths: Sun Jan 11 13:36:37 2009 1 relations: 41032 Sun Jan 11 13:36:37 2009 2 relations: 37329 Sun Jan 11 13:36:37 2009 3 relations: 36815 Sun Jan 11 13:36:37 2009 4 relations: 33907 Sun Jan 11 13:36:37 2009 5 relations: 31185 Sun Jan 11 13:36:37 2009 6 relations: 27422 Sun Jan 11 13:36:37 2009 7 relations: 24890 Sun Jan 11 13:36:37 2009 8 relations: 21712 Sun Jan 11 13:36:37 2009 9 relations: 18849 Sun Jan 11 13:36:37 2009 10+ relations: 86037 Sun Jan 11 13:36:37 2009 heaviest cycle: 19 relations Sun Jan 11 13:36:38 2009 commencing cycle optimization Sun Jan 11 13:36:38 2009 start with 2306192 relations Sun Jan 11 13:36:46 2009 pruned 71150 relations Sun Jan 11 13:36:46 2009 memory use: 59.1 MB Sun Jan 11 13:36:46 2009 distribution of cycle lengths: Sun Jan 11 13:36:46 2009 1 relations: 41032 Sun Jan 11 13:36:46 2009 2 relations: 38368 Sun Jan 11 13:36:46 2009 3 relations: 38384 Sun Jan 11 13:36:46 2009 4 relations: 35109 Sun Jan 11 13:36:46 2009 5 relations: 32245 Sun Jan 11 13:36:46 2009 6 relations: 28176 Sun Jan 11 13:36:46 2009 7 relations: 25251 Sun Jan 11 13:36:46 2009 8 relations: 21807 Sun Jan 11 13:36:46 2009 9 relations: 19046 Sun Jan 11 13:36:46 2009 10+ relations: 79760 Sun Jan 11 13:36:46 2009 heaviest cycle: 19 relations Sun Jan 11 13:36:47 2009 Sun Jan 11 13:36:47 2009 commencing linear algebra Sun Jan 11 13:36:47 2009 read 359178 cycles Sun Jan 11 13:36:48 2009 cycles contain 1219899 unique relations Sun Jan 11 13:37:11 2009 read 1219899 relations Sun Jan 11 13:37:13 2009 using 20 quadratic characters above 67106504 Sun Jan 11 13:37:29 2009 building initial matrix Sun Jan 11 13:37:49 2009 memory use: 143.3 MB Sun Jan 11 13:37:50 2009 read 359178 cycles Sun Jan 11 13:37:54 2009 matrix is 358916 x 359178 (101.8 MB) with weight 34240490 (95.33/col) Sun Jan 11 13:37:54 2009 sparse part has weight 24159762 (67.26/col) Sun Jan 11 13:38:04 2009 filtering completed in 3 passes Sun Jan 11 13:38:04 2009 matrix is 356391 x 356591 (101.3 MB) with weight 34051114 (95.49/col) Sun Jan 11 13:38:04 2009 sparse part has weight 24052492 (67.45/col) Sun Jan 11 13:38:10 2009 read 356591 cycles Sun Jan 11 13:38:34 2009 matrix is 356391 x 356591 (101.3 MB) with weight 34051114 (95.49/col) Sun Jan 11 13:38:34 2009 sparse part has weight 24052492 (67.45/col) Sun Jan 11 13:38:34 2009 saving the first 48 matrix rows for later Sun Jan 11 13:38:34 2009 matrix is 356343 x 356591 (97.5 MB) with weight 27064086 (75.90/col) Sun Jan 11 13:38:34 2009 sparse part has weight 23420867 (65.68/col) Sun Jan 11 13:38:34 2009 matrix includes 64 packed rows Sun Jan 11 13:38:34 2009 using block size 65536 for processor cache size 2048 kB Sun Jan 11 13:38:39 2009 commencing Lanczos iteration Sun Jan 11 13:38:39 2009 memory use: 94.9 MB Sun Jan 11 14:23:46 2009 lanczos error: submatrix is not invertible Sun Jan 11 14:23:46 2009 lanczos halted after 8286 iterations (dim = 523979) Sun Jan 11 14:23:46 2009 linear algebra failed; retrying... Sun Jan 11 14:23:46 2009 commencing Lanczos iteration Sun Jan 11 14:23:46 2009 memory use: 94.9 MB Sun Jan 11 14:54:33 2009 lanczos halted after 5635 iterations (dim = 356340) Sun Jan 11 14:54:34 2009 recovered 31 nontrivial dependencies Sun Jan 11 14:54:35 2009 Sun Jan 11 14:54:35 2009 commencing square root phase Sun Jan 11 14:54:35 2009 reading relations for dependency 1 Sun Jan 11 14:54:35 2009 read 178125 cycles Sun Jan 11 14:54:35 2009 cycles contain 748833 unique relations Sun Jan 11 14:54:56 2009 read 748833 relations Sun Jan 11 14:55:01 2009 multiplying 607892 relations Sun Jan 11 14:57:15 2009 multiply complete, coefficients have about 24.15 million bits Sun Jan 11 14:57:17 2009 initial square root is modulo 8637493 Sun Jan 11 15:00:19 2009 prp48 factor: 432285313041719300052871390761329367297291202031 Sun Jan 11 15:00:19 2009 prp60 factor: 114560369726709893553301074140392913347253937166681264885463 Sun Jan 11 15:00:19 2009 elapsed time 01:29:31 What's that? A hardware glitch / cosmic ray hitting my CPU? (I reran the factorization starting with the same relations on my C2D and did not get this error.) Edit: Logfile of my run on the C2D laptop: Code: Sun Jan 11 14:33:07 2009 Sun Jan 11 14:33:07 2009 Sun Jan 11 14:33:07 2009 Msieve v. 1.39 Sun Jan 11 14:33:07 2009 random seeds: a38734c0 afc5c328 Sun Jan 11 14:33:07 2009 factoring 49522765289485889233681931153717435991979703139426318174911416089221747128358987182858892932767806807975353 (107 digits) Sun Jan 11 14:33:08 2009 searching for 15-digit factors Sun Jan 11 14:33:10 2009 commencing number field sieve (107-digit input) Sun Jan 11 14:33:10 2009 R0: -438344816114060314814 Sun Jan 11 14:33:10 2009 R1: 132924059497 Sun Jan 11 14:33:10 2009 A0: -111978409899830736166589619 Sun Jan 11 14:33:10 2009 A1: 10900893999882414321130 Sun Jan 11 14:33:10 2009 A2: -73456024489071382 Sun Jan 11 14:33:10 2009 A3: -14805200109600 Sun Jan 11 14:33:10 2009 A4: 94944591 Sun Jan 11 14:33:10 2009 A5: 3060 Sun Jan 11 14:33:10 2009 skew 36845.15, size 5.659998e-011, alpha -5.326807, combined = 3.341570e-010 Sun Jan 11 14:33:10 2009 Sun Jan 11 14:33:10 2009 commencing relation filtering Sun Jan 11 14:33:10 2009 commencing duplicate removal, pass 1 Sun Jan 11 14:34:04 2009 found 347625 hash collisions in 4744132 relations Sun Jan 11 14:34:23 2009 added 1 free relations Sun Jan 11 14:34:23 2009 commencing duplicate removal, pass 2 Sun Jan 11 14:34:33 2009 found 324399 duplicates and 4419734 unique relations Sun Jan 11 14:34:33 2009 memory use: 43.3 MB Sun Jan 11 14:34:33 2009 reading rational ideals above 2949120 Sun Jan 11 14:34:33 2009 reading algebraic ideals above 2949120 Sun Jan 11 14:34:33 2009 commencing singleton removal, pass 1 Sun Jan 11 14:35:27 2009 relations with 0 large ideals: 110838 Sun Jan 11 14:35:27 2009 relations with 1 large ideals: 695096 Sun Jan 11 14:35:27 2009 relations with 2 large ideals: 1569426 Sun Jan 11 14:35:27 2009 relations with 3 large ideals: 1492049 Sun Jan 11 14:35:27 2009 relations with 4 large ideals: 502184 Sun Jan 11 14:35:27 2009 relations with 5 large ideals: 20134 Sun Jan 11 14:35:27 2009 relations with 6 large ideals: 30007 Sun Jan 11 14:35:27 2009 relations with 7+ large ideals: 0 Sun Jan 11 14:35:27 2009 4419734 relations and about 4338337 large ideals Sun Jan 11 14:35:27 2009 commencing singleton removal, pass 2 Sun Jan 11 14:36:19 2009 found 1969447 singletons Sun Jan 11 14:36:19 2009 current dataset: 2450287 relations and about 1970706 large ideals Sun Jan 11 14:36:19 2009 commencing singleton removal, pass 3 Sun Jan 11 14:36:50 2009 found 462026 singletons Sun Jan 11 14:36:50 2009 current dataset: 1988261 relations and about 1474077 large ideals Sun Jan 11 14:36:50 2009 commencing singleton removal, final pass Sun Jan 11 14:37:17 2009 memory use: 37.3 MB Sun Jan 11 14:37:17 2009 commencing in-memory singleton removal Sun Jan 11 14:37:17 2009 begin with 1988261 relations and 1515227 unique ideals Sun Jan 11 14:37:19 2009 reduce to 1664708 relations and 1182437 ideals in 16 passes Sun Jan 11 14:37:19 2009 max relations containing the same ideal: 47 Sun Jan 11 14:37:20 2009 reading rational ideals above 720000 Sun Jan 11 14:37:20 2009 reading algebraic ideals above 720000 Sun Jan 11 14:37:20 2009 commencing singleton removal, final pass Sun Jan 11 14:37:46 2009 keeping 1421676 ideals with weight <= 20, new excess is 187057 Sun Jan 11 14:37:47 2009 memory use: 46.7 MB Sun Jan 11 14:37:47 2009 commencing in-memory singleton removal Sun Jan 11 14:37:48 2009 begin with 1664708 relations and 1421676 unique ideals Sun Jan 11 14:37:50 2009 reduce to 1651370 relations and 1408316 ideals in 15 passes Sun Jan 11 14:37:50 2009 max relations containing the same ideal: 20 Sun Jan 11 14:37:51 2009 removing 139455 relations and 126421 ideals in 13034 cliques Sun Jan 11 14:37:51 2009 commencing in-memory singleton removal Sun Jan 11 14:37:51 2009 begin with 1511915 relations and 1408316 unique ideals Sun Jan 11 14:37:52 2009 reduce to 1503826 relations and 1273724 ideals in 8 passes Sun Jan 11 14:37:52 2009 max relations containing the same ideal: 20 Sun Jan 11 14:37:53 2009 removing 101984 relations and 88950 ideals in 13034 cliques Sun Jan 11 14:37:53 2009 commencing in-memory singleton removal Sun Jan 11 14:37:53 2009 begin with 1401842 relations and 1273724 unique ideals Sun Jan 11 14:37:53 2009 reduce to 1396543 relations and 1179439 ideals in 7 passes Sun Jan 11 14:37:53 2009 max relations containing the same ideal: 20 Sun Jan 11 14:37:54 2009 relations with 0 large ideals: 15120 Sun Jan 11 14:37:54 2009 relations with 1 large ideals: 105699 Sun Jan 11 14:37:54 2009 relations with 2 large ideals: 301461 Sun Jan 11 14:37:54 2009 relations with 3 large ideals: 437312 Sun Jan 11 14:37:54 2009 relations with 4 large ideals: 344428 Sun Jan 11 14:37:54 2009 relations with 5 large ideals: 148752 Sun Jan 11 14:37:54 2009 relations with 6 large ideals: 38263 Sun Jan 11 14:37:54 2009 relations with 7+ large ideals: 5508 Sun Jan 11 14:37:54 2009 commencing 2-way merge Sun Jan 11 14:37:56 2009 reduce to 826080 relation sets and 608976 unique ideals Sun Jan 11 14:37:56 2009 commencing full merge Sun Jan 11 14:38:07 2009 memory use: 46.5 MB Sun Jan 11 14:38:07 2009 found 385653 cycles, need 359176 Sun Jan 11 14:38:07 2009 weight of 359176 cycles is about 25500227 (71.00/cycle) Sun Jan 11 14:38:07 2009 distribution of cycle lengths: Sun Jan 11 14:38:07 2009 1 relations: 41038 Sun Jan 11 14:38:07 2009 2 relations: 37302 Sun Jan 11 14:38:07 2009 3 relations: 36818 Sun Jan 11 14:38:07 2009 4 relations: 33878 Sun Jan 11 14:38:07 2009 5 relations: 31174 Sun Jan 11 14:38:07 2009 6 relations: 27493 Sun Jan 11 14:38:07 2009 7 relations: 24872 Sun Jan 11 14:38:07 2009 8 relations: 21684 Sun Jan 11 14:38:07 2009 9 relations: 18882 Sun Jan 11 14:38:07 2009 10+ relations: 86035 Sun Jan 11 14:38:07 2009 heaviest cycle: 19 relations Sun Jan 11 14:38:07 2009 commencing cycle optimization Sun Jan 11 14:38:08 2009 start with 2306467 relations Sun Jan 11 14:38:14 2009 pruned 71206 relations Sun Jan 11 14:38:14 2009 memory use: 59.1 MB Sun Jan 11 14:38:14 2009 distribution of cycle lengths: Sun Jan 11 14:38:14 2009 1 relations: 41038 Sun Jan 11 14:38:14 2009 2 relations: 38347 Sun Jan 11 14:38:14 2009 3 relations: 38386 Sun Jan 11 14:38:14 2009 4 relations: 35075 Sun Jan 11 14:38:14 2009 5 relations: 32238 Sun Jan 11 14:38:14 2009 6 relations: 28236 Sun Jan 11 14:38:14 2009 7 relations: 25238 Sun Jan 11 14:38:14 2009 8 relations: 21790 Sun Jan 11 14:38:14 2009 9 relations: 19075 Sun Jan 11 14:38:14 2009 10+ relations: 79753 Sun Jan 11 14:38:14 2009 heaviest cycle: 19 relations Sun Jan 11 14:38:15 2009 Sun Jan 11 14:38:15 2009 commencing linear algebra Sun Jan 11 14:38:15 2009 read 359176 cycles Sun Jan 11 14:38:16 2009 cycles contain 1219904 unique relations Sun Jan 11 14:38:37 2009 read 1219904 relations Sun Jan 11 14:38:39 2009 using 20 quadratic characters above 67106504 Sun Jan 11 14:38:48 2009 building initial matrix Sun Jan 11 14:39:04 2009 memory use: 143.3 MB Sun Jan 11 14:39:04 2009 read 359176 cycles Sun Jan 11 14:39:09 2009 matrix is 358916 x 359176 (101.8 MB) with weight 34242477 (95.34/col) Sun Jan 11 14:39:09 2009 sparse part has weight 24161895 (67.27/col) Sun Jan 11 14:39:15 2009 filtering completed in 3 passes Sun Jan 11 14:39:15 2009 matrix is 356378 x 356578 (101.3 MB) with weight 34051136 (95.49/col) Sun Jan 11 14:39:15 2009 sparse part has weight 24053165 (67.46/col) Sun Jan 11 14:39:26 2009 read 356578 cycles Sun Jan 11 14:39:48 2009 matrix is 356378 x 356578 (101.3 MB) with weight 34051136 (95.49/col) Sun Jan 11 14:39:48 2009 sparse part has weight 24053165 (67.46/col) Sun Jan 11 14:39:48 2009 saving the first 48 matrix rows for later Sun Jan 11 14:39:48 2009 matrix is 356330 x 356578 (97.5 MB) with weight 27064648 (75.90/col) Sun Jan 11 14:39:48 2009 sparse part has weight 23421599 (65.68/col) Sun Jan 11 14:39:48 2009 matrix includes 64 packed rows Sun Jan 11 14:39:48 2009 using block size 65536 for processor cache size 4096 kB Sun Jan 11 14:39:52 2009 commencing Lanczos iteration Sun Jan 11 14:39:52 2009 memory use: 94.9 MB Sun Jan 11 14:59:38 2009 lanczos halted after 5636 iterations (dim = 356328) Sun Jan 11 14:59:39 2009 recovered 32 nontrivial dependencies Sun Jan 11 14:59:40 2009 Sun Jan 11 14:59:40 2009 commencing square root phase Sun Jan 11 14:59:40 2009 reading relations for dependency 1 Sun Jan 11 14:59:40 2009 read 177839 cycles Sun Jan 11 14:59:40 2009 cycles contain 747735 unique relations Sun Jan 11 15:00:00 2009 read 747735 relations Sun Jan 11 15:00:04 2009 multiplying 606662 relations Sun Jan 11 15:01:47 2009 multiply complete, coefficients have about 24.10 million bits Sun Jan 11 15:01:48 2009 initial square root is modulo 8362163 Sun Jan 11 15:04:11 2009 reading relations for dependency 2 Sun Jan 11 15:04:11 2009 read 177507 cycles Sun Jan 11 15:04:11 2009 cycles contain 747061 unique relations Sun Jan 11 15:04:31 2009 read 747061 relations Sun Jan 11 15:04:35 2009 multiplying 606718 relations Sun Jan 11 15:06:19 2009 multiply complete, coefficients have about 24.10 million bits Sun Jan 11 15:06:20 2009 initial square root is modulo 8365739 Sun Jan 11 15:08:42 2009 reading relations for dependency 3 Sun Jan 11 15:08:42 2009 read 178069 cycles Sun Jan 11 15:08:43 2009 cycles contain 748967 unique relations Sun Jan 11 15:09:03 2009 read 748967 relations Sun Jan 11 15:09:07 2009 multiplying 608248 relations Sun Jan 11 15:10:50 2009 multiply complete, coefficients have about 24.16 million bits Sun Jan 11 15:10:52 2009 initial square root is modulo 8716289 Sun Jan 11 15:13:13 2009 reading relations for dependency 4 Sun Jan 11 15:13:13 2009 read 177853 cycles Sun Jan 11 15:13:14 2009 cycles contain 748192 unique relations Sun Jan 11 15:13:35 2009 read 748192 relations Sun Jan 11 15:13:48 2009 multiplying 607722 relations Sun Jan 11 15:15:31 2009 multiply complete, coefficients have about 24.15 million bits Sun Jan 11 15:15:32 2009 initial square root is modulo 8606929 Sun Jan 11 15:17:53 2009 prp48 factor: 432285313041719300052871390761329367297291202031 Sun Jan 11 15:17:53 2009 prp60 factor: 114560369726709893553301074140392913347253937166681264885463 Sun Jan 11 15:17:53 2009 elapsed time 00:44:46 4 dependencies needed to find the factors - vs one in the P4 retry? Why the difference? Last fiddled with by Andi47 on 2009-01-11 at 14:21 Reason: put lines with error in bold / red font
 2009-01-11, 14:56 #2 jasonp Tribal Bullet     Oct 2004 353710 Posts This is the first time I've seen a Lanczos run reach >100% and actually terminate (with an error). It appears to happen once in a while, and failures of the sort listed are not impossible according to the theory behind block Lanczos. If, as is more likely, there's a well-hidden bug in the code, I have no clue how to go about fixing it. Regarding the different number of dependencies, this is because the library chooses a random start vector when performing the linear algebra. Even if the matrix is exactly the same between two machines, this implies that the dependencies found will be different from run to run. When the input has two factors, each dependency has a 2-in-3 chance of being nontrivial but you "reroll the dice" every time a new batch of dependencies is computed.
2009-01-11, 15:09   #3
Andi47

Oct 2004
Austria

2×17×73 Posts

Quote:
 Originally Posted by jasonp This is the first time I've seen a Lanczos run reach >100% and actually terminate (with an error). It appears to happen once in a while, and failures of the sort listed are not impossible according to the theory behind block Lanczos. If, as is more likely, there's a well-hidden bug in the code, I have no clue how to go about fixing it. Regarding the different number of dependencies, this is because the library chooses a random start vector when performing the linear algebra. Even if the matrix is exactly the same between two machines, this implies that the dependencies found will be different from run to run. When the input has two factors, each dependency has a 2-in-3 chance of being nontrivial but you "reroll the dice" every time a new batch of dependencies is computed.
So even when the error is not reproducible between two machines, this is no prove for a hardware error on my first machine?

BTW: about trying to fix a possible elusive bug: What about printing the start vector to the logfile? This might make it somewhat easier to track it down.

Edit: I still have got the matrix - if you want to have it for testing, I could upload it and give you the link. (I assume that you need the msieve.dat.mat file.)

Edit2: About running above 100% and terminating: Fivemack had some matrices to run beyond 100% and AFIK he stopped these runs manually. So possible these ones might have terminated themselves too, but who wants to run a matrix up to 146% when this takes an additional week or two?

Last fiddled with by Andi47 on 2009-01-11 at 16:09 Reason: edit3: corrected filename according to 10metreh's post

2009-01-11, 16:06   #4
10metreh

Nov 2008

44228 Posts

Quote:
 Originally Posted by Andi47 I assume that you need the msieve.mat.dat file.
And I assume that you need the msieve.dat.mat file.

2009-01-11, 16:08   #5
Andi47

Oct 2004
Austria

2×17×73 Posts

Quote:
 Originally Posted by 10metreh And I assume that you need the msieve.dat.mat file.
*grrrr* sorry, mistyped it.

 2009-01-11, 17:29 #6 jasonp Tribal Bullet     Oct 2004 33×131 Posts I don't have the time to do more research on this problem. I think automatically quitting with an error when the number of dimensions exceeds maybe 105% of the maximum expected is a good idea.
2009-01-11, 17:33   #7
Andi47

Oct 2004
Austria

9B216 Posts

Quote:
 Originally Posted by jasonp I don't have the time to do more research on this problem. I think automatically quitting with an error when the number of dimensions exceeds maybe 105% of the maximum expected is a good idea.
Why not 100.5%? Is there any chance for a matrix to succeed when the number of dimensions exceeds 100% of the maximum expected?

This question went unanswered:

Quote:
 Originally Posted by Andi47 So even when the error is not reproducible between two machines, this is no prove for a hardware error on my first machine? (addition: i.e. getting an error one time and none the other time could still be caused by software related things like choosing a random starting vector?)

Last fiddled with by Andi47 on 2009-01-11 at 17:33 Reason: )

 2009-01-11, 19:33 #8 jasonp Tribal Bullet     Oct 2004 33×131 Posts I don't know if it's possible to get a completed matrix solution if the iterations go over 100%; it's never happened but that doesn't mean it's impossible. Yes, in theory the code could be working perfectly and merely have chosen a bad starting vector. I have seen the 'matrix not invertible' error occur before reaching 100%, and all the times it has happened there was never a question about the stability of the underlying machine. Block Lanczos is not a good stress test for the memory system anyway, because the amount of tuning I've had time to perform on the code is quite minimal. Last fiddled with by jasonp on 2009-01-11 at 19:34

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