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2012-09-16, 18:43   #78
jrk

May 2008

3·5·73 Posts

Quote:
 Originally Posted by Dubslow Code: lanczos error: only trivial dependencies found
This is the problem.

Try running -nc again with only 15M relations.

2012-09-16, 19:10   #79
Dubslow

"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

11100001101012 Posts

Quote:
 Originally Posted by jrk This is the problem. Try running -nc again with only 15M relations.
Oh, I didn't even see that.

How would too many relations cause only trivial dependencies? Or is it that the BL algorithm fails somehow?

I'll truncate the rel file and try again.

2012-09-16, 20:22   #80
Dubslow

"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

3·29·83 Posts

Quote:
 Originally Posted by Dubslow Oh, I didn't even see that. How would too many relations cause only trivial dependencies? Or is it that the BL algorithm fails somehow? I'll truncate the rel file and try again.
Thanks again, that did the trick, although the matrix took quite a bit longer to solve. (50 minutes; though it was actually smaller, it was also about +20 weight/col more dense.)

 2012-09-17, 01:42 #81 jasonp Tribal Bullet     Oct 2004 DCE16 Posts Nobody is sure, but even with other packages an NFS matrix will become impossible to solve with enough oversieving.
2012-09-17, 01:47   #82
Dubslow

"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

160658 Posts

Quote:
 Originally Posted by jasonp Nobody is sure, but even with other packages an NFS matrix will become impossible to solve with enough oversieving.

What about with Gaussian Elimination? Theoretically, as long as there are more columns than rows...

 2012-09-17, 02:34 #83 LaurV Romulan Interpreter     Jun 2011 Thailand 220738 Posts x+y=7 2x+2y=14 3x+3y=21 etc. Solve?
2012-09-17, 02:46   #84
Dubslow

"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

3×29×83 Posts

Quote:
 Originally Posted by LaurV x+y=7 2x+2y=14 3x+3y=21 etc. Solve?
There's an infinite number of solutions, though I'm not sure what this has to do with anything, because were not solving for the null space of ((1,1),(2,2),(3,3)) by finding (x,y), and this certainly has more rows than columns...

 2012-09-17, 03:37 #85 LaurV Romulan Interpreter     Jun 2011 Thailand 220738 Posts Grrr, scrap that! I tried to play smart a before the morning coffee... Right now I understood what you wanted to say...
 2012-09-17, 05:25 #86 Kosmaj     Nov 2003 2·1,811 Posts Has anybody tried to factor 1000+ digit numbers with Yafu? (Of course, sieving methods cannot be used, but Yafu is still better than plain ecm to automate the process, and keep track of found factors.) The other day I started with 3 numbers with about 1600 digits, everything was working great, and I reached t30 without any problems. Then I switched to numbers with about 1000-1020 digits, a few of them were all right, then problems began. On one number Yafu crashed with an "unrecognized character on input line" kind of error, on the next one with "too many allocs or frees" error. I'm not sure but it seems it happened when Yafu was about to start ecm. The above was with Yafu-1.32.1 on linux (no external ecm), with the same version on Windows-7 Yafu crashed on the very first of these numbers (which Yafu on linux was able to process). This is all happening in the batch mode, with "pretest -plan custom" and "-pretest_ratio" 0.02 or 0.03. BTW, is there a way to tell Yafu to stop ecm on a particular fixed level, say t30, independent of the size of the input number? "-preset_ratio" works but it accepts only 2 fractional digits, if I try 0.025 it is converted to 0.03. Even with preset_ratio accepting more fractional digits, an option like "preset_level t30" will be better. Thanks!
2012-09-17, 10:53   #87
jasonp
Tribal Bullet

Oct 2004

2·3·19·31 Posts

Quote:
 Originally Posted by Dubslow Talk about counter-intuitive. What about with Gaussian Elimination? Theoretically, as long as there are more columns than rows...
It isn't that simple; if there are more columns than rows but some of those columns are linear combinations of each other, then you may not have a nontrivial nullspace. My theory is that this is what happens when you have too much oversieving, matrix columns start to look more and more alike because the relations that contribute to them get mixed together too much.

2012-09-17, 13:42   #88
bsquared

"Ben"
Feb 2007

3,371 Posts

Quote:
 Originally Posted by Kosmaj Has anybody tried to factor 1000+ digit numbers with Yafu? (Of course, sieving methods cannot be used, but Yafu is still better than plain ecm to automate the process, and keep track of found factors.) The other day I started with 3 numbers with about 1600 digits, everything was working great, and I reached t30 without any problems. Then I switched to numbers with about 1000-1020 digits, a few of them were all right, then problems began. On one number Yafu crashed with an "unrecognized character on input line" kind of error, on the next one with "too many allocs or frees" error. I'm not sure but it seems it happened when Yafu was about to start ecm. The above was with Yafu-1.32.1 on linux (no external ecm), with the same version on Windows-7 Yafu crashed on the very first of these numbers (which Yafu on linux was able to process). This is all happening in the batch mode, with "pretest -plan custom" and "-pretest_ratio" 0.02 or 0.03. BTW, is there a way to tell Yafu to stop ecm on a particular fixed level, say t30, independent of the size of the input number? "-preset_ratio" works but it accepts only 2 fractional digits, if I try 0.025 it is converted to 0.03. Even with preset_ratio accepting more fractional digits, an option like "preset_level t30" will be better. Thanks!
Other people have reported problems when the input size is right around 1024 characters. Coincidentally, most of the character buffers in yafu are initialized to 1024 characters. They are supposed to grow as necessary, and given that 1600 digit inputs work they seem to be doing that, but it looks like there are issues when the inputs are close to the overflow point. I'll look into it.

There is no way that I know of to have yafu stop at a certain t-level, but I don't think it would be hard to add.

Thanks for the feedback.

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