pqc/external/flint-2.4.3/fmpz_poly/sub.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) 2008, 2009 William Hart
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_poly.h"
void
_fmpz_poly_sub(fmpz * res, const fmpz * poly1, slong len1, const fmpz * poly2,
slong len2)
{
slong i, min = FLINT_MIN(len1, len2);
for (i = 0; i < min; i++) /* subtract up to the length of the shorter poly */
fmpz_sub(res + i, poly1 + i, poly2 + i);
if (poly1 != res) /* copy any remaining coefficients from poly1 */
for (i = min; i < len1; i++)
fmpz_set(res + i, poly1 + i);
/* careful, it is *always* necessary to negate coeffs from poly2, even if this is already res */
for (i = min; i < len2; i++)
fmpz_neg(res + i, poly2 + i);
}
void
fmpz_poly_sub(fmpz_poly_t res, const fmpz_poly_t poly1,
const fmpz_poly_t poly2)
{
slong max = FLINT_MAX(poly1->length, poly2->length);
fmpz_poly_fit_length(res, max);
_fmpz_poly_sub(res->coeffs, poly1->coeffs, poly1->length, poly2->coeffs,
poly2->length);
_fmpz_poly_set_length(res, max);
_fmpz_poly_normalise(res); /* there may have been cancellation */
}