104 lines
2.7 KiB
C
104 lines
2.7 KiB
C
/*=============================================================================
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This file is part of FLINT.
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FLINT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FLINT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2011 Fredrik Johansson
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******************************************************************************/
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/*
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Demo FLINT program for balanced multimodular reduction and
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reconstruction using the Chinese Remainder Theorem.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include "flint.h"
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#include "fmpz.h"
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#include "ulong_extras.h"
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int main(int argc, char* argv[])
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{
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slong i;
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fmpz_t x, y;
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/* Data needed by multi CRT functions */
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fmpz_comb_t comb;
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fmpz_comb_temp_t comb_temp;
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mp_limb_t * primes;
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mp_limb_t * residues;
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slong num_primes;
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if (argc != 3)
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{
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flint_printf("Syntax: crt <integer> <num_primes>\n");
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return EXIT_FAILURE;
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}
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num_primes = atoi(argv[2]);
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if (num_primes < 1)
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{
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flint_printf("Requires num_primes >= 1\n");
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return EXIT_FAILURE;
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}
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fmpz_init(x);
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fmpz_init(y);
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fmpz_set_str(x, argv[1], 10);
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primes = flint_malloc(num_primes * sizeof(mp_limb_t));
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residues = flint_malloc(num_primes * sizeof(mp_limb_t));
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primes[0] = 2;
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for (i = 1; i < num_primes; i++)
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primes[i] = n_nextprime(primes[i-1], 0);
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fmpz_comb_init(comb, primes, num_primes);
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fmpz_comb_temp_init(comb_temp, comb);
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/* Reduce modulo all primes */
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fmpz_multi_mod_ui(residues, x, comb, comb_temp);
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/* Reconstruct */
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fmpz_multi_CRT_ui(y, residues, comb, comb_temp, 1);
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for (i = 0; i < num_primes; i++)
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flint_printf("residue mod %wu = %wu\n", primes[i], residues[i]);
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flint_printf("reconstruction = ");
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fmpz_print(y);
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flint_printf("\n");
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fmpz_clear(x);
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fmpz_clear(y);
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fmpz_comb_temp_clear(comb_temp);
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fmpz_comb_clear(comb);
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flint_free(residues);
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flint_free(primes);
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return EXIT_SUCCESS;
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}
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