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