_mp_alloc vs ALLOC

Torbjorn Granlund tg at gmplib.org
Mon Jun 4 20:27:53 CEST 2012

bodrato at mail.dm.unipi.it writes:

  IIRC someone proposed to change the meaning of the second argument of
  mpz_probab_prime_p. Now it is documented as "reps controls how many
  [Miller-Rabin] tests are done". It should be something like "logprob
  controls the likeliness of a wrong answer, the function will return
  probably prime for a composite with a probability of 1 over 2^logprob".
I think new functions should probably work like that.  We could also
export mpz_millerrabin, and there allow for a count (or let users call
it repeatedly).

int mpz_pprime_p (mpz_t N, gmp_randstate_t *rs, int logprob)

(How to estimate the probablity is non-obvious.  Depending on the
smoothness of N-1 Miller-Rabin will be more or less effective...)


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