20130226, 17:38  #12  
"Ben"
Feb 2007
41×83 Posts 
Quote:
Also, thanks for your own contributions. I appreciate your willingness to dive in anywhere in the codebase and help out. Along those lines, thanks again to all developers, beta testers, and bug reporters. YAFU is getting way too big for me to handle on my own. 

20130227, 03:16  #13 
Mar 2010
38_{16} Posts 
Factoring the C128 from 10^154+19 using 1.34:
GNFS elapsed time: 41060 SNFS elapsed time: 7196 Woooo! Thanks so much for making this happen! 
20130227, 20:05  #14 
"Ben"
Feb 2007
41·83 Posts 
I just updated sourceforge with 1.34.3 binaries (and related source) that contains a bugfix. <fingers crossed> Hopefully this is the last one
TL;DR section: One of the recent changes involved me updating all of the related factorization packages that are linked into yafu (GMP, MPIR, msieve, and GMPECM). This I did with varying degrees of clumsiness, the result being the bug referenced above. Now all of the associated libraries and headers should be consistent, and as a bonus, yafu now uses MPIR 2.6.0, GMP 5.1.1, and GMPECM 6.4.2. Happy factoring! 
20130228, 13:17  #15  
Mar 2006
11·43 Posts 
Quote:
All you have to do is type: aprcl(10^199+153) And you can prove this 200 digit number prime in just a few seconds! Just so you can get an idea of how long it will take to prove the primality of various sized numbers, here is a short list of times on my computer: Code:
100 digits : 5^143+2 : 0.3125s 150 digits : 3^313*4+5 : 1.1719s 200 digits : 7^235*9+2 : 3.0469s 250 digits : 5^356*81 : 6.4844s 300 digits : 424^114+3 : 12.7344s 350 digits : 1160^114+7 : 23.6563s 400 digits : (291^1631)/290 : 39.3281s 450 digits : 232^190+7 : 58.0313s 500 digits : 1014^166+7 : 88.1406s 550 digits : 10^549*97 : 147.4688s 600 digits : 1432^190+7 : 210.3281s 650 digits : 2^2159+375 : 265.9844s 700 digits : (157^319+319^157)/28 : 403.0781s 750 digits : 10^749*2+89 : 519.9531s 800 digits : (10^799*617)/9 : 709.7500s 850 digits : 2^2821183 : 974.4688s 900 digits : (24^6531)/23 : 1063.8125s 950 digits : 10^949*49 : 1422.8125s 1000 digits : 10^999+7 : 1588.3125s Happy factoring and/or prime proving! 

20130228, 14:02  #16 
Mar 2010
2^{3}×7 Posts 
I just factored a C148 with SNFS in 26 hours (vs. ~120 with GNFS).
I must say it would appear SNFS is a better bet than long ECM runs. The C128 that took 2 hours with SNFS  I figure ECM for no more than 30 minutes should be fine before sending it to SNFS. I think the crossover point from ECM to SNFS is somewhere between 125 and 135 digits on my system. 
20130228, 14:40  #17 
"Ben"
Feb 2007
3403_{10} Posts 
That sounds about right. The commonly used rule of thumb is 2/9 of the snfs difficulty in ecm. So if the difficulty of your c128 is also 128 (they need not be the same!) then ecm to t28.4 (or, if you know the c128 will take 2 hours to snfs, then ecm for 26.7 minutes).
Last fiddled with by bsquared on 20130228 at 15:00 Reason: 'y' 
20130301, 03:42  #18 
Jun 2012
5^{2}×7×17 Posts 
I feel dumb asking this question, but how do I force GNFS poly search even on a special form composite? There are situations where GNFS is prefered over SNFS.
When I run yafu 1.34 it only does SNFS poly search on my xyyx type composite. The np flag does not change this behavior. Still playing with 1.34, and so far the new functionality rocks. The additional primality tests are impressive. I'm not very familiar with them, but it's nice to be able to run several rigorous tests that identify a number as being "almost certainly" prime in a short time. 
20130301, 05:02  #19 
"Ben"
Feb 2007
41·83 Posts 
That... is not a dumb question at all. In fact it seems I've overlooked that possibility At least, nothing is occurring to me as to a way to force it to use gnfs. I guess we'll have at least one more patch to 1.34 at some point. I'll try to get it done tomorrow.

20130301, 06:22  #20 
Romulan Interpreter
Jun 2011
Thailand
10010010010111_{2} Posts 
I know! I know! Pick me! Pick me!
You have to find a factor using ECM, first. Then, as B2 said before, it will not detect that the remaining composite comes from a SNFSable form, and it will do GNFS... 
20130301, 08:22  #21 
Banned
"Luigi"
Aug 2002
Team Italia
17·283 Posts 

20130301, 11:21  #22  
Jun 2012
5^{2}·7·17 Posts 
Quote:
[begin obligatory xyyx pitch]Come on over and try it for yourself! Lots of composites needing to be factored.[/pitch] 

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