gmp prime testing

[Torbjorn Granlund]

Jason Moxham <J.L.Moxham@maths.soton.ac.uk> writes:

  > > Currently gmp has prime tables to 1000 , which takes 168*2 bytes , prime
  > > table to 65536 would take 13K , prime difference to 65536 would take 6.4K
  > > . if this is too much
  >
  > Don't know.  I'm hoping Torbjorn will make that decision.  :-)
  
  yes
  
I have code that adds primes tables up to 65536 for GMP 4.2, just not
yet checked in.

  > > construct_and_use_prime_table(global_prime_table_pointer,limits);
  >
  > PARI does something like that, it's nice and flexible for
  > applications.
  >
  > > you would call this at a "thread safe time"
  >
  > Yes, we don't want to get intimate with the thread manager.
  >
  > > ul	mpz_trial_div(mpz_srcptr N , ul start , ul stop)
  >
  > Sounds fair to me, if Torbjorn likes it.

Might make sense.  What is it supposed to return?
Any factor, or 1 (or 0?) if no factor is found.

Not that we wouldn't want to guarantee prime factors,
we might want to accumulate several factors and then use gcd
to find out if they divide N.

-- 
Torbjörn