----- Original Message ----- From: "Daran" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, June 10, 2002 6:54 AM Subject: Re: Mersenne: P-1 Puzzle
> This appears to have happened to me at least once. I'll spend some time > later today cross-referencing my WTD file against pminus1.txt to see if > there are any more I don't need to do. Yesterday morning, shortly after 6 UTC, I reserved 42 DC exponents between 7.08M and 7.74M, i.e. all were recently expired exponents. Of these 27 had the P-1 bit set, all of which were P-1 complete, according to the pminus1.txt file dated June 9. Of the 15 with P-1 bit clear, one was in fact P-1 complete. I also reserved 32 test exponents between 12.7 and 13.8M. Of these, 27 had the P-1 bit set, 5 clear. None of these disagreed with pminus1.txt. Finally I checked 28 DC exponents which I had previously reserved, between 7.23M and 7.74M. All had the P-1 bit clear. (I routinely unreserve any exponents I get with P-1 bit set.) Of these, two were P-1 complete. >From this, admittedly small and non-random sample, it appears that about one-third of *reassignments* of expired DC exponents have the P-1 bit clear, and that about one in fifteen of these are incorrect, leading to a redundant P-1 rerun by the new owner. I don't know what proportion of DC assignments are reassignments, but given that P-1 testing takes about 2% of the time to run a DC test, I would suggest that the impact of this problem upon the project as a whole is negligible. However, for anyone processing a lot of exponents, particularly those specialising in collecting reassignments, it might be worth putting together a script to identify these anomalies. >With 512MB I probably have considerably more available memory > than the average machine doing DCs now. That will be less true for > machines doing DCs in the future, and probably not true at all for > machines doing first time tests. Inspecting pminus1.txt confirms this. I would do a 796xxxx DC exponent with B1=45000,B2=675000. Ignoring those which were obviously P-1ed as first-time test exponents, or where the tester has chosen to go well beyond the optimal limits, there are very few in this range which have been factored deeper than this, and many which have had stage 1 only or a very limited stage 2. I would do a 1550xxxx test exponent with B1=190000,B2=4227500, which is better than average, but not to the same extent as with the DC range. And I can P-1 many DC assignments in the time I'd take to do a single test assignment. I'd do a 10M digit exponent with B1=375000,B2=8156250, still better than average, but there are quite a few that go much deeper. Very noticable is the proportion of exponents - in all three ranges - which are not getting a stage two effort at all. 26 out the 85 exponents between 7950000 and 796000, 24 out of 54 between 15500000 and 15505000, 35 out of 57 between 33219000 and 33223000. I do not believe that large numbers of P4 systems are being shipped with just 8MB of RAM! Regards Daran _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
