primorial(negative)

[Torbjörn Granlund]

paul zimmermann <Paul.Zimmermann at inria.fr> writes:

  you can also consider the file utils/getprime.c from CADO-NFS:
  
  zimmerma at tarte:~/svn/cado-nfs/utils$ gcc -O3 -g -DMAIN getprime.c
  zimmerma at tarte:~/svn/cado-nfs/utils$ time ./a.out 1000000000
  pi(1000000000)=50847534
  
  real    0m2.572s
  user    0m2.268s
  sys     0m0.000s
  
  This is almost 1000 times faster than GMP.
  
1000 times faster than mpz_nextprime, sure.  But that's not a very fair
comparison as one is set up to generate many primes while the other is
set up to generate one prime at a time.

Here is some new code:

$ gcc49 -std=c99 -O2 ehb3sieve.c && /usr/bin/time ./a.out 1000000000
0.55user 0.00system 0:00.55elapsed 99%CPU

Which is more than 4 times faster than CADO-NFS.  :-)

  
-- 
Torbjörn
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