Subject: bug#12350: Composites identified as primes in factor.c (when HAVE_GMP)

From: Torbjorn Granlund <[email-masked]>
Date: Tue, 04 Sep 2012 20:10:59 +0200

Pádraig Brady <[email-masked]> writes:

  On 09/04/2012 03:46 PM, Jim Meyering wrote:
  > There are 9008992 composites of the form with s=2 below 2^64.  With 3
  > Miller-Rabin test, one would expect about 9008992/4^64 = 140766 to be
  
  s/4^64/64/ ?
  
  For what it's worth I checked the million primes in
  the range 452,930,477 to 472,882,027 and they're
  now identified correctly (465658903 was included previously).
  
  Note processing time has increased with the patch.
  On my 2.1GHz i3-2310M, running over the above range
  used to take 14m, but now takes 18m.
  
It sometimes takes more time to do things correctly.

As I mentioned in the original post, we will replace the current code
with code that is many times faster.  Your example above will run at
less than a minute on your system.

-- 
Torbjörn