Re: Mersenne: M727 has a factor?!?!?
Will Edgington wrote: > > P-1 on P727 with B1=30, B2=1 > P727 stage 1 complete. 116 transforms. Time: 0.018 sec. >(4659194 clocks) > Stage 1 GCD complete. Time: 0.001 sec. (164887 clocks) > P727 has a factor: 11633 > > This meets all the criteria too > 1) 11633 is PRIME. > 2) 2kp+1 = 2*(8)*727+1 = 11633 > 3) 8n+1 = 8*(1454)+1 = 11633 > 4) 2^p (mod n) = 2^727 (mod 11633) = 1 > >11633 divides M1454 where 1454 = 2*727, but 11633 does not >divide M727. Your #4 calculation has a bug, probably a >rounding error; the correct result is 11631. Well, I went back and did it by hand!! You're right about #4... BTW, George wrote that what I got was a result of a parsing error on the part of Prime95 (it did 2^727+1, not 2^727-1). R = 1 727 = 1011010111 E=727D=1R=2A=4 E=363D=1R=8A= 16 E=181D=1R= 128A= 256 E= 90D=0R= 128A= 7371 E= 45D=1R= 1215A= 5531 E= 22D=0R= 1215A= 8804 E= 11D=1R= 6133A=11370 E= 5D=1R= 4008A=11004 E= 2D=0R= 4008A= 119 E= 1D=1R=11632A= 2528 E= 0*11632* Eric _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: M727 has a factor?!?!?
> >Hi!! > > Tell me I'm wrong... and if not, what happened?? >P727 has a factor: 11633 Look carefully: that's P727, which denotes 2^727+1. You must have accidentally specified "factor 2^n+1" when you started the work. This small factor was reported because there is no entry in LOWP.TXT for P727; it was removed after P727 was finished last year--by me, incidentally. Alas, P727's evil twin M727 remains unfactored. David A. Miller [EMAIL PROTECTED] _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Mersenne: M727 has a factor?!?!?
P-1 on P727 with B1=30, B2=1 P727 stage 1 complete. 116 transforms. Time: 0.018 sec. (4659194 clocks) Stage 1 GCD complete. Time: 0.001 sec. (164887 clocks) P727 has a factor: 11633 This meets all the criteria too 1) 11633 is PRIME. 2) 2kp+1 = 2*(8)*727+1 = 11633 3) 8n+1 = 8*(1454)+1 = 11633 4) 2^p (mod n) = 2^727 (mod 11633) = 1 11633 divides M1454 where 1454 = 2*727, but 11633 does not divide M727. Your #4 calculation has a bug, probably a rounding error; the correct result is 11631. In fact: M( 1454 )C: 11633 M( 1454 )C: 52068472442119144511578580563 M( 1454 )C: 59803996769241650545074361210286131 M( 1454 )D That is, M1454 is considered to be completely factored even though it is a multiple of M727, which is known to be composite but has no known prime factors. There are other cases like this in the data. >From my "reverse method" program, I should now have all factors less than about 1.6 billion for _any_ Mersenne number with an exponent less than 2^30 (just over a billion). Will http://www.garlic.com/~wedgingt/mersenne.html _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Mersenne: M727 has a factor?!?!?
Hi!! Tell me I'm wrong... and if not, what happened?? I just made a slight error in adding a P-1 factor assignment to the WORKTODO.INI file for M727 and came up with the following result (on screen): P-1 on P727 with B1=30, B2=1 P727 stage 1 complete. 116 transforms. Time: 0.018 sec. (4659194 clocks) Stage 1 GCD complete. Time: 0.001 sec. (164887 clocks) P727 has a factor: 11633 and in the RESULTS.TXT file: [Sat Apr 08 10:43:37 2000] P-1 found a factor in stage #1, B1=30, B2=1. UID: Net_Force/V20, P727 has a factor: 11633 This meets all the criteria too 1) 11633 is PRIME. 2) 2kp+1 = 2*(8)*727+1 = 11633 3) 8n+1 = 8*(1454)+1 = 11633 4) 2^p (mod n) = 2^727 (mod 11633) = 1 Eric P.S. the error in question was: Pminus1=727,1E16,0,0,0 _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: mprime on a Dell PowerEdge
On 8 Apr 00, at 7:00, Aaron Blosser wrote: > >I thought ECC memory was supposed to Correct any errors and continue, not > >just detect them. > > That's the idea. ECC can correct single bit errors and detect (but not > correct) 2 bit errors. And hopefully log the occurrence of any memory faults i.e. when a bit correction needed to be made. This gives you a good idea about how close to the wind you're sailing. One bit corrected per month is probably acceptable. > > Typically, such things are considered of less importance on a workstation, > which is also why you don't find RAID (or even SCSI) on many workstations > either... ... but price is a bigger issue. Most home users don't drive a system hard enough for the ultimate in speed to be a problem (RAID is most commonly used in conjunction with stripe sets to increase disk I/O bandwidth); as for reliability, home users, and purchasers of desktop systems for business, blame any hangs & crashes on the OS anyway, so why bother building reliable hardware when you can sell crap for $20 less? Regards Brian Beesley _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: mprime on a Dell PowerEdge
>John R Pierce wrote: >> yeah, ugh. Well, the system came with 256MB of PC133 ECC registered SDRAM >> (2 * 128MB), I've fortified it with an additional 1GB of PC133 ECC >> registered SDRAM (4 * 256MB). I would *hope* any memory error would trip a >> ECC error. >I thought ECC memory was supposed to Correct any errors and continue, >not just detect them. That's the idea. ECC can correct single bit errors and detect (but not correct) 2 bit errors. Compaq's memory design on their serers has ECC-2 which corrects 2 bit errors and can detect (but not correct) 4 bit errors. I don't know how common ECC-2 is among server designs from other companies... Typically, such things are considered of less importance on a workstation, which is also why you don't find RAID (or even SCSI) on many workstations either... Aaron _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: Prime 95 Speeds
>I worked that excel sheet up using the information available at >http://www.mersenne.org/bench.htm; Goerge, There still isn't a link to this page from youre pages. The current link still points to the old benchmark page _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: mprime on a Dell PowerEdge
John R Pierce wrote: > yeah, ugh. Well, the system came with 256MB of PC133 ECC registered SDRAM > (2 * 128MB), I've fortified it with an additional 1GB of PC133 ECC > registered SDRAM (4 * 256MB). I would *hope* any memory error would trip a > ECC error. I thought ECC memory was supposed to Correct any errors and continue, not just detect them. cheers... Russ _ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
