67 lines
2.2 KiB
C
67 lines
2.2 KiB
C
/*=============================================================================
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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) 2007, David Howden.
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Copyright (C) 2010 William Hart
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******************************************************************************/
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#include <stdlib.h>
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#include <gmp.h>
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#include "flint.h"
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#include "nmod_vec.h"
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#include "nmod_poly.h"
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void
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_nmod_poly_sub(mp_ptr res, mp_srcptr poly1, slong len1, mp_srcptr poly2,
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slong len2, nmod_t mod)
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{
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slong i, min = FLINT_MIN(len1, len2);
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_nmod_vec_sub(res, poly1, poly2, min, mod);
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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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res[i] = poly1[i];
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/*
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Careful, it is *always* necessary to negate coeffs from poly2,
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even if this is already res.
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*/
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for (i = min; i < len2; i++)
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res[i] = nmod_neg(poly2[i], mod);
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}
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void
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nmod_poly_sub(nmod_poly_t res, const nmod_poly_t poly1,
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const nmod_poly_t poly2)
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{
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slong max = FLINT_MAX(poly1->length, poly2->length);
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nmod_poly_fit_length(res, max);
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_nmod_poly_sub(res->coeffs, poly1->coeffs, poly1->length, poly2->coeffs,
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poly2->length, poly1->mod);
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res->length = max;
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_nmod_poly_normalise(res); /* there may have been cancellation */
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}
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