ECM for exponents above 20,000,000

[VBCurtis]

Originally Posted by PageFault

Can anyone recommend an ECM test for me? I like running bizarre work, the kind others won't touch. I am intrigued by ECM on low Mersenne numbers, such that I have a chance (albeit small) of finding a monster factor.
I can allocate 1350 MB of ram and don't care if the test takes months. I want to find a monster. I used to like P-1, but the gpu crowd effectively ruined that and TF as well.

You could pick a single number and do months of work on it, hundreds or thousands of curves; or you could choose a range of exponents and do a few dozen/hundred curves on each. The size of factor you'd search for is related to the size of the exponent- how small are you talking? For exponents under 5000, ecm has already been done to much higher bounds than for exponents around 1M, or higher.

If you choose an exponent under 1500 to concentrate effort upon, it is likely your ECM work will be of interest to future factoring efforts. You'll also be able to use GMP-ECM, which is faster than Prime95 at that size. A table of known factors 1200-1300 (includes non-prime exponents): http://homes.cerias.purdue.edu/~ssw/cun/xtend/main2mp

A list of links about factoring mersennes: http://www.garlic.com/~wedgingt/mersenne.html

Finally, to get an idea of what settings to use for a search for factors of a particular size: http://www.loria.fr/~zimmerma/records/ecm/params.html

So, what size exponent do you have in mind?

[PageFault]

Well, I'm asking for a recommendation - no time to read or fool around with anything, i.e. must use prime95 client, please post or PM a worktodo line..

How about ~ 750000 - 1000000 M, pick some exponents, to do a month, or several, on each? Or more, if it may be innaresting for future factoring efforts.

Thanks,

PF

[PageFault]

ECM2=F8FC338FC24CE5D099185B29AD7218DD,1,2,501013,-1,250000,25000000,150

OK - now what do I modify?

I got this manually - I don't think I can stick in worktodo without changing setting to manual? Otherwise I have to clear out all existing assignments.

Test=N/A before the ECM2?

[LaurV]

See here.

You don't need to post the same thing in many places. And don't post assignment keys, mask the hex stuff with xxxxx or .... chars. Some people here think it is not safe (one may "steal your work" if he has the assignment key).