20061216, 11:49  #1 
May 2005
England, UK
2^{7} Posts 
GMPECM and the Cunningham Input List
Forgive me if I am posting in the wrong thread.
Earlier this year I ran GMPECM on the Cunningham input list, using B1= 11e6, just like it says on the web page http://www.loria.fr/~zimmerma/ecmnet/ It took me 4 1/2 months, and no factors were found. Question. Is it likely that there are still factors to be found in the list using B1=11e6, or am I wasting my time? Should I do another run using B1=11e6, or should I be using B1=43e6? I would consider doing another run using B1=11e6 if it was thought that there were still factors waiting to be discovered using this value of B1. I don't think I can do a run using B1=43e6, as I would only be able to do one curve per day, and a full run on the Cunningham input list would take me over two years! 
20061216, 12:14  #2 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
I'd say B1=11M is suboptimal now. There's a small chance that even that will find a factor, but higher B1, say B1=44M or even 110M, will perform better.
I'll ask Paul to update the page. Alex Edit: Note that finding any Cunningham factors with ECM is very hard these days. A lot of ECM has been done already, largely thanks to Bruce Dodson, and the easy pickings a long gone. Last fiddled with by akruppa on 20061216 at 12:17 
20061216, 14:16  #3 
May 2005
England, UK
2^{7} Posts 
OK, thanks for the reply.
I don't think that I can help out with the ECMNET project any further, as my computer is too old and slow to run curves with a higher value of B1. 
20061216, 23:00  #4  
"Jason Goatcher"
Mar 2005
3·7·167 Posts 
Quote:
If you want another project to run, may I suggest http://www.distributedcomputing.info for research? If you're still interested in ecm, there are other project possibilites, like the Odd Perfect Number search. 

20061219, 14:11  #5 
May 2005
England, UK
128_{10} Posts 
No, I am not giving up on distributed computing.
I am simply pointing out that many projects nowadays, like ECM, are much better done by faster, more modern computers than my old, nearly obsolete machine. Just this morning I started doing a factoring assignment for GIMPS, which should take me about a month to complete! 
20061219, 14:40  #6  
"Bob Silverman"
Nov 2003
North of Boston
5^{3}×61 Posts 
Quote:
to existing factoring projects. The Cunningham project requires a large amount of resources to run ECM or NFS succesfully on any of the remaining composites. Indeed, I no longer have sufficient machines to perform Cunningham NFS factorizations. This tends to discourage new participants. Which is one reason that I have been promoting the homogeneous Cunningham project. These have not been attempted with ECM to the same extent as the Cunningham project and results are obtainable for someone with only a single PC. 

20061219, 18:16  #7  
Jul 2003
Behind BB
2021_{10} Posts 
Quote:
http://www.leyland.vispa.com/numth/f.../anbn/main.htm trolling around... masser 

20061219, 18:39  #8  
Bamboozled!
"๐บ๐๐ท๐ท๐ญ"
May 2003
Down not across
2×5×1,187 Posts 
Quote:
Paul 

20061219, 19:00  #9  
"Bob Silverman"
Nov 2003
North of Boston
5^{3}·61 Posts 
Quote:
This will finish 3,2 to exponent 400. I will then do 6,5,218+ and 6,5,223+. There still remain some numbers with exponent divisible by 5 that are *very* easy among the remaining current composites. 

20061221, 13:59  #10 
Jun 2003
F4_{16} Posts 
Is there an organized effort to factors these Homogeneous Cunningham numbers? I'd like to know at least at what B1 level factoring should start and approximately how many curves to do at that level.

20061221, 14:13  #11  
"Bob Silverman"
Nov 2003
North of Boston
1DC9_{16} Posts 
Quote:
40 digits. 

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