16009Re: [PrimeNumbers] Help please... user or pgm bug with NewPGen 2.82 on AMD & P4
- Jan 30, 2005Chuck wrote:
> I sieved, for 24 hours as is (I am told) the norm using NPG.The norm for any sieve is to sieve until the removal rate is similar to the
prp/test time (which may be a complicated issue for a fixed k sieve).
> I did the most rudimentary test: k.b^n-1The prime 7*2^29-1 = 3758096383 is between 1G and 5G (G = 10^9).
> using: k=7, b=2, 2<=n<=65536
> @ P=1G, K=7,N=29 was in the NPG as the lowest file.
> @ P=5G, it was gone... as were MANY of valid K N
> (which would yield prime) values.
As Jim also thinks, NewPGen probably removed it when the prime was found as
factor of itself.
Some of my sieves knowingly do the same.
Users and programmers can argue about whether something is a bug or feature.
If NewPGen also removes some known primes above the sieve limit:
Can you give examples?
Have you checked "Verify results" ?
The help says:
If "Verify results" is checked, NewPGen will do a careful check to make sure
that the prime actually does divide the number that it thinks it does. This
will make NewPGen very slightly slower, but it is recommended that it is
always checked, particularly as p gets large (where the scope for programming
If you check "Log the numbers removed" in the Options menu then NewPGen will
write which prime removes a candidate, but only for primes above 2^32.
Jens Kruse Andersen
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