pqc/external/flint-2.4.3/fmpz_mod_poly_factor/is_squarefree.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
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
Copyright (C) 2012 Lina Kulakova
******************************************************************************/
#include "fmpz_mod_poly.h"
#include "fmpz_vec.h"
#include "ulong_extras.h"
#include <string.h>
int
_fmpz_mod_poly_is_squarefree(const fmpz * f, slong len, const fmpz_t p)
{
fmpz * fd, * g;
fmpz_t invd;
slong dlen;
int res;
if (len <= 2)
return len != 0;
fd = _fmpz_vec_init(2 * (len - 1));
g = fd + len - 1;
_fmpz_mod_poly_derivative(fd, f, len, p);
dlen = len - 1;
FMPZ_VEC_NORM(fd, dlen);
if (dlen)
{
fmpz_init(invd);
fmpz_invmod(invd, fd + dlen - 1, p);
res = (_fmpz_mod_poly_gcd(g, f, len, fd, dlen, invd, p) == 1);
fmpz_clear(invd);
}
else
res = 0; /* gcd(f, 0) = f, and len(f) > 2 */
_fmpz_vec_clear(fd, 2 * (len - 1));
return res;
}
int fmpz_mod_poly_is_squarefree(const fmpz_mod_poly_t f)
{
return _fmpz_mod_poly_is_squarefree(f->coeffs, f->length, &f->p);
}