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/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2011 Fredrik Johansson
******************************************************************************/
/*
Demo FLINT program for balanced multimodular reduction and
reconstruction using the Chinese Remainder Theorem.
*/
#include <stdlib.h>
#include <stdio.h>
#include "flint.h"
#include "fmpz.h"
#include "ulong_extras.h"
int main(int argc, char* argv[])
{
slong i;
fmpz_t x, y;
/* Data needed by multi CRT functions */
fmpz_comb_t comb;
fmpz_comb_temp_t comb_temp;
mp_limb_t * primes;
mp_limb_t * residues;
slong num_primes;
if (argc != 3)
{
flint_printf("Syntax: crt <integer> <num_primes>\n");
return EXIT_FAILURE;
}
num_primes = atoi(argv[2]);
if (num_primes < 1)
{
flint_printf("Requires num_primes >= 1\n");
return EXIT_FAILURE;
}
fmpz_init(x);
fmpz_init(y);
fmpz_set_str(x, argv[1], 10);
primes = flint_malloc(num_primes * sizeof(mp_limb_t));
residues = flint_malloc(num_primes * sizeof(mp_limb_t));
primes[0] = 2;
for (i = 1; i < num_primes; i++)
primes[i] = n_nextprime(primes[i-1], 0);
fmpz_comb_init(comb, primes, num_primes);
fmpz_comb_temp_init(comb_temp, comb);
/* Reduce modulo all primes */
fmpz_multi_mod_ui(residues, x, comb, comb_temp);
/* Reconstruct */
fmpz_multi_CRT_ui(y, residues, comb, comb_temp, 1);
for (i = 0; i < num_primes; i++)
flint_printf("residue mod %wu = %wu\n", primes[i], residues[i]);
flint_printf("reconstruction = ");
fmpz_print(y);
flint_printf("\n");
fmpz_clear(x);
fmpz_clear(y);
fmpz_comb_temp_clear(comb_temp);
fmpz_comb_clear(comb);
flint_free(residues);
flint_free(primes);
return EXIT_SUCCESS;
}
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