Re: Good GMP performance (WAS Re: Problems linking with gmp...)

[Torbjorn Granlund]

Will Galway <address@hidden> writes:

  At some later date I'll probably send out a note asking for advice on
  getting a higher-performance modular exponentiation routine, in the
  hopes that I can do better than mpz_powm (which is what I'm using
  now).  The speed at which I can do modular exponentiations is the
  limiting factor in a computation I'm currently working on (searching
  for pseudoprimes).  I'm hoping that I can do significantly better than
  mpz_powm because for this application my needs are limited to
  computing 2^k modulo n, where both k and n are (unsigned) 64-bit
  integers.  Using mpz_powm, it looks like I'm getting roughly 10^5
  modular exponentiations per second on a 1.2 GHz Athlon....
  
Hack something in low-level C with umul_ppmm fro longlong.h.
Don't bother with the rest of GMP.

-- 
Torbjörn