Jim,

I understand that it calculates b^(N-1)%N, does PFGW first set (N-1)= (2^k)*D, where D is odd, to take advantage of calculating b^(N-1)%N or does it go through one exponent at a time until it reaches (N-1)?

jim_fougeron <

jfoug@...> wrote:

For checking a prp, pfgw simply computes:

b^(N-1)%N and checks to see if the result of that is equal to 1.

If you "try" to perform a prp-11 check on 11 (and tell PFGW to

NOT perform any trivial factoring at all), then PFGW will claim

that 11 is composite. This is because 11^10%11 == 0 and the

ONLY value PFGW is looking for is b^(N-1)%N == 1.

--- In

primenumbers@yahoogroups.com, Cletus Emmanuel <cemmanu@y...>

wrote:

> Hi all,

> When checking for PRP, how does PFGW handle this task? For

example, if the base and the number to be checked is N=11, does PFGW

check 2^1 mod 11, 2^2mod 11, 2^3 mod 11, etc. Or does it check 2^2

mod 11 and 2^5 mod 11. In other words, does it check every single

exponent from 1 to N-1 or does it check only the prime divisors of N-

1?

>

> ---Cletus

>

>

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