pqc/external/flint-2.4.3/fmpz_poly/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) 2010 Sebastian Pancratz
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpz_poly.h"
#include "fmpq_poly.h"
int _fmpz_poly_is_squarefree(const fmpz * poly, slong len)
{
if (len < 3)
{
return 1;
}
else if (len == 3)
{
int ans;
fmpz_t lhs, rhs;
fmpz_init(lhs);
fmpz_init(rhs);
fmpz_mul(lhs, poly + 1, poly + 1);
fmpz_mul(rhs, poly, poly + 2);
fmpz_mul_ui(rhs, rhs, 4);
ans = !fmpz_equal(lhs, rhs);
fmpz_clear(lhs);
fmpz_clear(rhs);
return ans;
}
else
{
int ans;
fmpz * w = _fmpz_vec_init(2 * len);
_fmpz_poly_derivative(w, poly, len);
_fmpz_poly_gcd(w + len, poly, len, w, len - WORD(1));
ans = _fmpz_vec_is_zero(w + len + 1, len - 2);
_fmpz_vec_clear(w, 2 * len);
return ans;
}
}
int fmpz_poly_is_squarefree(const fmpz_poly_t poly)
{
return _fmpz_poly_is_squarefree(poly->coeffs, poly->length);
}