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Old 2019-01-05, 17:04   #4
kriesel's Avatar
Mar 2017
US midwest

16AF16 Posts

Originally Posted by robertfrost View Post
Thanks. ... What's the syntax for an ECM p-1 test?
1) You're welcome, and welcome to the GIMPS forum.
2) I don't know; what color is an apple orange?

ECM and P-1 are two different factoring methods. P-1 is available for gpus. ECM is not available for gpus in implementations supporting enough bits for exponents of current GIMPS interest at the first test or double check wavefront.

If you're intending to ask about gmp-ecm's syntax for attempting P-1 factoring, I refer you to its documentation. Note, I tried it briefly long ago, and found it too slow to be useful, by comparison to prime95 and CUDAPm1, for exponents of current GIMPS wavefront size. It's my understanding it's intended for "smaller" numbers than GIMPS is concerned with currently. Every package has its strengths. GMP-ECM's usefulness lies elsewhere.

CUDAPm1 syntax for worktodo is shown in its readme. Or get a manual assignment from (but only if you intend to complete it; if run time is too long for you, go to to unreserve it) and copy and paste the assignment in. If you want a copy of the assignment saved, create your own separate assignment log text file, or put it in worktodo twice, and put # in front of one of them to make the line into a comment that will linger. Note, depending on what gpu you have, and choice of assignments, P-1 assignments can take hours, days, weeks, or months. (Years in extreme cases. Avoid those. Very long run times are unlikely to produce correct results. Also CUDAPm1 v0.20 fails to complete on highest exponents currently, above 176M to 430M depending on gpu model, and it can take days to months to hit the point of failure, wasting a long time, which is no fun. V0.22 may also have this issue.)

Last fiddled with by kriesel on 2019-01-05 at 17:19
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