mersenneforum.org Any interest in some low n ECM factoring?
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 2005-08-08, 16:36 #1 ltd     Apr 2003 22·193 Posts Any interest in some low n ECM factoring? Hi, i am doing some ECM factoring on low n. Anyone interested to help me out a little bit? And yes i know it will not bring the project ahead i am doing it just for fun. Lars
 2005-08-08, 17:36 #2 OmbooHankvald     May 2005 Copenhagen, Denmark 172 Posts Care to explain a not-mathematician what it's about and how you do it? I've got my Pentium M 1.6 GHz laptop (not running 24/7) which (when I'm finished with S/R B5) I might consider using for other stuff, maybe this. Last fiddled with by OmbooHankvald on 2005-08-08 at 17:38
 2005-08-08, 18:20 #3 Citrix     Jun 2003 3·5·107 Posts Could you post a list of k and n you want to factor. I could run some curves. (what bounds you want us to run will be helpful) Citrix Ps: I am going to use http://www.alpertron.com.ar/ECM.HTM
 2005-08-08, 18:34 #4 ltd     Apr 2003 22×193 Posts I will try my best to describe it and hope that somebody else corrects all my errors. There are several methods to find a factor for a given number. For example we use sieving to find factors for as many numbers as possible before we do a PRP test to check if a number is prime or not. At the moment we find factors that are 13 Digits long with sieving. There are other methods called "p-1","p+1" and ECM. These methods can find factors that are much longer but it takes also alot of time time compared to do a PRP test. Don't ask me about the math behind it. I just know how to set up a test. For the fun of finding some large factors (30 digits and larger at the moment) i started to run p-1 and ECM on all non factored k/n pairs with n less then 2000. There are 26 n left where i found no factor less then 25 digits. (For the experts B1=50000) For 13 of them i also finished the 30 digit level (B1=250000) and for the other 13 i should have finished that level in 2 days. To help you can use either Prime95 or ECM6. I am using ECM6. Lars
 2005-08-08, 18:38 #5 Citrix     Jun 2003 64516 Posts Where do you get the binaries for ECM6? You only want to find the lowest factor or factorize the whole number? Citrix
 2005-08-08, 18:45 #6 ltd     Apr 2003 22·193 Posts Here is a list of the values that need ECM at B1=1000000. To complete this B1 level each of the numbers needs 950 curves. 237019*2^1006+1 : 1*10^6 | 60 : done 152267*2^1059+1 : 1*10^6 | 61 : done 168451*2^1116+1 : 1*10^6 | 60 : done 265711*2^1128+1 : 1*10^6 | 60 : done 149183*2^1157+1 : 1*10^6 | 60 : done 258317*2^1167+1 79817*2^1191+1 214519*2^1194+1 222113*2^1221+1 149183*2^1309+1 258317*2^1311+1 237019*2^1330+1 265711*2^1344+1 : 1*10^6 | 1 : done The other 13 ( hopefully less) will follow when i have finished B1=250000. 237019*2^1006+1 is my most wanted as it is the lowest unfactored n. @Citrix: As far as i know the the ECM you want to use is slow compared to ECM6. I have precompiled windows version for P3,P4,Athlon and Athlon64. ( No i did not make the compilation but found the links somewhere here in one of the forums) Lars Last fiddled with by ltd on 2005-08-09 at 15:53
 2005-08-08, 18:49 #7 Citrix     Jun 2003 3·5·107 Posts Could you provide me a link to the binary for p4! (or upload it or email it to me). I will try to look in the other forms. I will start with 152267*2^1059+1 Citrix
 2005-08-08, 18:53 #8 ltd     Apr 2003 22·193 Posts I found the binaries under the following link: http://www.pa.uky.edu/~childers/ecm6.zip If you want to read the thread where if found the link: http://www.mersenneforum.org/showthr...6&page=3&pp=50 I only want to find one factor and not the complete factorisation so you should use the "-one" option. Lars
 2005-08-08, 19:02 #9 OmbooHankvald     May 2005 Copenhagen, Denmark 172 Posts I'll guide again I've collected pieces of information around here on the forums and I've come up with this as a basic guide to how to compile an exe which suits your own system. I hope it's correct...
 2005-08-08, 19:26 #10 Citrix     Jun 2003 3·5·107 Posts I will return my k, I can't get the exe to work. Though I did 1 curve using the applet. Citrix
 2005-08-08, 19:27 #11 Citrix     Jun 2003 3·5·107 Posts Ill try p-1. What bounds have you used for p-1, though it seems unlikely that I will find a factor. Citrix

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