mpir/tests/mpz/t-pprime_p.c

/* Exercise mpz_probab_prime_p.

Copyright 2002 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.

The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA. */

#include <stdio.h>
#include <stdlib.h>
#include "mpir.h"
#include "gmp-impl.h"
#include "tests.h"


/* Enhancements:

   - Test some big primes don't come back claimed to be composite.
   - Test some big composites don't come back claimed to be certainly prime.
   - Test some big composites with small factors are identified as certainly
     composite.  */


/* return 1 if prime, 0 if composite */
int
isprime (long n)
{
  long  i;

  n = ABS(n);

  if (n < 2)
    return 0;
  if (n == 2)
    return 1;
  if ((n & 1) == 0)
    return 0;

  for (i = 3; i < n; i++)
    if ((n % i) == 0)
      return 0;

  return 1;
}

void
check_one (mpz_srcptr n, int want)
{
  int  got;

  got = mpz_probab_prime_p (n, 25);

  /* "definitely prime" is fine if we only wanted "probably prime" */
  if (got == 2 && want == 1)
    want = 2;

  if (got != want)
    {
      printf ("mpz_probab_prime_p\n");
      mpz_trace ("  n    ", n);
      printf    ("  got =%d", got);
      printf    ("  want=%d", want);
      abort ();
    }
}

void
check_pn (mpz_ptr n, int want)
{
  check_one (n, want);
  mpz_neg (n, n);
  check_one (n, want);
}

/* expect certainty for small n */
void
check_small (void)
{
  mpz_t  n;
  long   i;

  mpz_init (n);

  for (i = 0; i < 300; i++)
    {
      mpz_set_si (n, i);
      check_pn (n, isprime (i));
    }

  mpz_clear (n);
}

int
main (void)
{
  tests_start ();

  check_small ();

  tests_end ();
  exit (0);
}