Hi all,
At 03:49 PM 5/18/2001 +0000, Denis Cazor wrote:
>1) When testing a new Pc, I obtain two different results from the old and
>the new one
>
>M9357637 is not prime. Res64: BCB1164E6826255E. WW1: C4F561C3,5448242,00000000
>M9357637 is not prime. Res64: BCB1164E6826255E. WW1: C4F261C3,5448242,00030000
>
>Are this results compatible ?
Sigh, the rarely read readme.txt file says:
M1992031 is not prime. Res64: 6549369F4962ADE0. WV1: B253EF24,1414032,00000000
This means 2^1992031-1 is not prime - a Lucas-Lehmer test says so.
The last 64 bits of the last number in the Lucas-Lehmer sequence
is 6549369F4962ADE0. At some future date, another person will verify
this 64-bit result by rerunning the Lucas-Lehmer test. WV1 is the
program version number. B253EF24 is a checksum to guard against email
transmission errors. 1414032 can be ignored it is used as part
of the double-checking process. The final 00000000 value is a set
of 4 counters. These count the number of errors that occurred during
the Lucas-Lehmer test.
To elaborate, the 5448242 in your run is the shift count. Since your 2 runs
had an identical shift count, you undoubtedly started the second test using
a save file produced somewhere during the first test. An exponent will not
be considered double-checked unless the two runs have different shift counts.
The 00030000 shows that you had 3 ILLEGAL SUMOUT errors on one
machine and no errors on the other. The four counters - one byte each -
are: count of reproducible errors, count of illegal sumouts, count of
roundoff > 0.40, count of sum(inputs) != sum(outputs).
>2)
>It seems Prime95 is beginning the calculus two early (?) and produce
>ILLEGAL SUMOUT ERROR.
>Instead of waiting five minutes, I can stop prime (test/stop menu) then
>continue
>(test/ continue menu). Theire are no more errors after that.
This suggestion is actually a high priority for the next release. The
error is probably caused by some driver or program initialization that isn't
saving the FPU state properly. The error is benign as you found out.
I think the main advantage of this feature is it will lead to slightly faster
boot times and thereby improve prime95's reputation of not interfering with
your everyday work.
Regards,
George
_________________________________________________________________________
Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
