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2014-10-27, 18:06   #320
bsquared

"Ben"
Feb 2007

3,371 Posts

Quote:
 Originally Posted by swellman I just got a new box and a twist on this bug has appeared. When I run the snfs() command, yafu starts to run then gives an error of "can't open log file" and crashes. The error is repeatable, though the place at which it crashes seems semi-random. Sometimes it crashes at the first poly, sometimes after quite a few. Changing number of threads seems to help, though I don't know why (doesn't the snfs() command only use 1 thread?). But the snfs() command never gets to the test sieving step, just crashes in the poly generation phase. The number I am running is C158_136_134 from the xyyx project. Code: 84311455579199090648493230576403161968451360234506586342094132063229517346160992903240099249802174895769891679510634920540783201237119607493881630083817780573 System AMD E2-6110 APU with AMD Radeon R2 Graphics 1.50 GHz RAM is 4.00 Gb Win 81. 64-bit with x64-based processor Anyway, another data point.
Thanks for the info.

So, I re-built MPIR 2.6.0, gmp-ecm 6.4.4, and then yafu, after which everything appears to work on windows (Msys). This one runs fine (yafu ultimately picks GNFS), the previous one picked a poly and started test sieving, and this bug is also fixed.

 2014-10-27, 20:18 #321 swellman     Jun 2012 B9016 Posts Great news! I will rerun the bug cases on my machines, though I'm traveling this week so it may be a few days until I get to it. Thanks for all the work.
2014-10-27, 20:42   #322
bsquared

"Ben"
Feb 2007

3,371 Posts

Quote:
 Originally Posted by swellman Great news! I will rerun the bug cases on my machines, though I'm traveling this week so it may be a few days until I get to it. Thanks for all the work.
Ok, but just to be clear, I haven't changed anything in either SVN or the downloadable executable... so you would have to rebuild everything yourself to see things fixed.

 2014-10-27, 21:25 #323 swellman     Jun 2012 24×5×37 Posts Ok - I (wrongly) assumed souceforge had been updated with all the executables. I can't compile on Windows. Will just have to wait for it to be compiled/tested/released formally. But you found the underlying problem, which is very cool.
 2014-11-13, 16:57 #324 mickfrancis   Apr 2014 Marlow, UK 23×7 Posts YAFU rho() performance 'bug'? Hi Ben, Pollard Rho probably isn't of much interest, but in case it is: I just spotted what appears to be a typo in rho.c around line 195: Code:  for(i=0;i<=r;i++) { mpz_mul(t1,y,y); //y = (y*y + c) mod n mpz_add_ui(t1, t1, c); mpz_tdiv_r(t1, t1, fobj->rho_obj.gmp_n); } I think this line should be: Code:  mpz_tdiv_r(y, t1, fobj->rho_obj.gmp_n); Running rho("188686371167044582826981915497892444670204038509658079137") (which is a P17.P40) the change brings the time down from 159s to 84s. Also, I think the loop should start at i=1 rather than i=0 (or have < rather than <=), though I could be wrong... Cheers, Mick.
 2014-11-24, 21:09 #325 skan     Apr 2012 2×47 Posts it would be great if somebody could upload a compiled Windows x64 binary with the latest corrected code, please.
 2014-12-05, 07:49 #326 storflyt32   Feb 2013 2×229 Posts Apparently Yafu is having a bug when it is factoring a number which is consisting of many small factors. This is the main reason for why I usually do not choose to be doing just such a thing. Factoring a number gives like a C230 from a C240 and the rest or remainder of the number is being listed without further factorization or stating whether it is composite or not. That is when using the ecm command. Using ecm(ans,30) instead, where ans is the current number (or the number currently being factored makes it possibly to return the result to the Factor Database either using the Auto detect (slow) format or Yafu output at the bottom of the pull-down menu. When using the ecm(ans,30) command, the remainder of the number is being listed as a P1234567891 (or P10). For the ecm(ans) command, I only get 1234567891 as the remainder of the result. This is a silly and unncessesary bug which needs to be fixed as soon as possible!
 2014-12-05, 08:09 #327 legendarymudkip     Jun 2014 23·3·5 Posts ECM runs ECM factoring on the number, it isn't supposed to completely factorise the number.
 2014-12-23, 21:58 #328 storflyt32   Feb 2013 2·229 Posts One small thing I notice in the Yafu output is that it is a bit cramped at times. Really I prefer to compress things myself and also when writing stuff trying to even out the sentences and not put everything in one single line or paragraph. But just one blank line for separating the different result elements in the output gives a better look or appearance of things. There are a couple of times where I am missing this blank line. Hopefully a small bug that could be fixed. Last fiddled with by storflyt32 on 2014-12-23 at 21:59
 2015-02-09, 00:19 #329 Dubslow Basketry That Evening!     "Bunslow the Bold" Jun 2011 40
 2015-02-09, 00:55 #330 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 2×4,663 Posts Of course it is a yafu issue! [/semi-sarcasm] yafu should be patched to reply: x^4-1 = (x-1)(x+1)(x^2+1) ...which immediately takes care of that particular example: it gets fully factored. More generally, yafu should not ever accept a reducible polynomial as a factorization hint. Either bluntly dump it back to the user, or factor it algebraically internally, and only then use the part that contains the input (or as in this case: take gcd, and divide-and-conquer).

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