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Annotation of OpenXM_contrib/gmp/demos/primes.c, Revision 1.1.1.1

1.1       maekawa     1: /* List and count primes.
                      2:
                      3: Copyright (C) 2000 Free Software Foundation, Inc.
                      4:
                      5: This program is free software; you can redistribute it and/or modify it under
                      6: the terms of the GNU General Public License as published by the Free Software
                      7: Foundation; either version 2 of the License, or (at your option) any later
                      8: version.
                      9:
                     10: This program is distributed in the hope that it will be useful, but WITHOUT ANY
                     11: WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
                     12: PARTICULAR PURPOSE.  See the GNU General Public License for more details.
                     13:
                     14: You should have received a copy of the GNU General Public License along with
                     15: this program; if not, write to the Free Software Foundation, Inc., 59 Temple
                     16: Place - Suite 330, Boston, MA 02111-1307, USA.  */
                     17:
                     18: #include <stdlib.h>
                     19: #include <stdio.h>
                     20: #include "gmp.h"
                     21:
                     22: /* Sieve table size */
                     23: #define ST_SIZE 30000
                     24: /* Largest prime to sieve with */
                     25: #define MAX_S_PRIME 1000
                     26:
                     27: main (int argc, char **argv)
                     28: {
                     29:   char *progname = argv[0];
                     30:   mpz_t r0, r1;                        /* range */
                     31:   mpz_t cur;
                     32:   unsigned char *st;
                     33:   unsigned long i, ii;
                     34:   unsigned long nprimes = 0;
                     35:   unsigned long last;
                     36:   int flag_print = 1;
                     37:   int flag_count = 0;
                     38:
                     39:   st = malloc (ST_SIZE);
                     40:
                     41:   while (argc != 1)
                     42:     {
                     43:       if (strcmp (argv[1], "-c") == 0)
                     44:        {
                     45:          flag_count = 1;
                     46:          argv++;
                     47:          argc--;
                     48:        }
                     49:       else if (strcmp (argv[1], "-p") == 0)
                     50:        {
                     51:          flag_print = 2;
                     52:          argv++;
                     53:          argc--;
                     54:        }
                     55:       else
                     56:        break;
                     57:     }
                     58:
                     59:   if (flag_count)
                     60:     flag_print--;              /* clear unless an explicit -p  */
                     61:
                     62:   mpz_init (r0);
                     63:   mpz_init (r1);
                     64:   mpz_init (cur);
                     65:
                     66:   if (argc == 2)
                     67:     {
                     68:       mpz_set_ui (r0, 2);
                     69:       mpz_set_str (r1, argv[1], 0);
                     70:     }
                     71:   else if (argc == 3)
                     72:     {
                     73:       mpz_set_str (r0, argv[1], 0);
                     74:       if (argv[2][0] == '+')
                     75:        {
                     76:          mpz_set_str (r1, argv[2] + 1, 0);
                     77:          mpz_add (r1, r1, r0);
                     78:        }
                     79:       else
                     80:        mpz_set_str (r1, argv[2], 0);
                     81:     }
                     82:   else
                     83:     {
                     84:       fprintf (stderr, "usage: %s [-c] [-g] [from [+]]to\n", progname);
                     85:       exit (1);
                     86:     }
                     87:
                     88:   if (mpz_cmp_ui (r0, 2) < 0)
                     89:     mpz_set_ui (r0, 2);
                     90:
                     91:   if ((mpz_get_ui (r0) & 1) == 0)
                     92:     {
                     93:       if (mpz_cmp_ui (r0, 2) == 0)
                     94:        {
                     95:          if (flag_print)
                     96:            puts ("2");
                     97:          nprimes++;
                     98:        }
                     99:       mpz_add_ui (r0, r0, 1);
                    100:     }
                    101:
                    102:   mpz_set (cur, r0);
                    103:
                    104:   while (mpz_cmp (cur, r1) <= 0)
                    105:     {
                    106:       memset (st, 1, ST_SIZE);
                    107:       for (i = 3; i < MAX_S_PRIME; i += 2)
                    108:        {
                    109:          unsigned long start;
                    110:          start = mpz_tdiv_ui (cur, i);
                    111:          if (start != 0)
                    112:            start = i - start;
                    113:
                    114:          if (mpz_cmp_ui (cur, i - start) == 0)
                    115:            start += i;
                    116:          for (ii = start; ii < ST_SIZE; ii += i)
                    117:            st[ii] = 0;
                    118:        }
                    119:       last = 0;
                    120:       for (ii = 0; ii < ST_SIZE; ii += 2)
                    121:        {
                    122:          if (st[ii] != 0)
                    123:            {
                    124:              mpz_add_ui (cur, cur, ii - last);
                    125:              last = ii;
                    126:              if (mpz_cmp (cur, r1) > 0)
                    127:                goto done;
                    128:              if (mpz_probab_prime_p (cur, 3))
                    129:                {
                    130:                  nprimes++;
                    131:                  if (flag_print)
                    132:                    {
                    133:                      mpz_out_str (stdout, 10, cur); puts ("");
                    134:                    }
                    135:                }
                    136:            }
                    137:        }
                    138:       mpz_add_ui (cur, cur, ST_SIZE - last);
                    139:     }
                    140:  done:
                    141:   if (flag_count)
                    142:     printf ("Pi(interval) = %lu\n", nprimes);
                    143:
                    144:   exit (0);
                    145: }