GMP-ECM and the Cunningham Input List

[M0CZY]

Forgive me if I am posting in the wrong thread.

Earlier this year I ran GMP-ECM 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!

[akruppa]

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.

[M0CZY]

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.

[jasong]

Originally Posted by M0CZY

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.

I really hope this doesn't mean you're going to quit Distributed Computing. I know you didn't say you were, I'm just saying I hope you aren't.

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.

[M0CZY]

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!

[R.D. Silverman]

Originally Posted by M0CZY

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!

Actually, I bemoan the fact that the bar is set very high for any newcomer
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.

[masser]

Originally Posted by R.D. Silverman

Actually, I bemoan the fact that the bar is set very high for any newcomer
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.

Here's the link to some information on the Homogeneous Cunningham project:

http://www.leyland.vispa.com/numth/f.../anbn/main.htm

trolling around...
masser

[xilman]

Originally Posted by masser

Here's the link to some information on the Homogeneous Cunningham project:

http://www.leyland.vispa.com/numth/f.../anbn/main.htm

trolling around...
masser

Indeed. And, as I said in another thread, as soon as the number of remaining composites on that page falls to 30 a new batch will be added. Some of those newcomers will surely have factors that are very easily found with ECM.

Paul

[R.D. Silverman]

Originally Posted by xilman

Indeed. And, as I said in another thread, as soon as the number of remaining composites on that page falls to 30 a new batch will be added. Some of those newcomers will surely have factors that are very easily found with ECM.

Paul

I will finish 3,2,379-, 379+, and 389- by the end of this week.
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.

[antiroach]

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.

[R.D. Silverman]

Originally Posted by antiroach

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.

It is not an organized effort. The numbers have been tested up to about
40 digits.