85 lines
2.8 KiB
C
85 lines
2.8 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) 2011 Sebastian Pancratz
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Copyright (C) 2010 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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#include "fmpz_mod_poly.h"
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void _fmpz_mod_poly_mul(fmpz *res, const fmpz *poly1, slong len1,
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const fmpz *poly2, slong len2, const fmpz_t p)
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{
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_fmpz_poly_mul(res, poly1, len1, poly2, len2);
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_fmpz_vec_scalar_mod_fmpz(res, res, len1 + len2 - 1, p);
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}
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void fmpz_mod_poly_mul(fmpz_mod_poly_t res,
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const fmpz_mod_poly_t poly1, const fmpz_mod_poly_t poly2)
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{
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const slong len1 = poly1->length;
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const slong len2 = poly2->length;
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const slong lenr = len1 + len2 - 1;
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if ((len1 == 0) || (len2 == 0))
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{
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fmpz_mod_poly_zero(res);
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return;
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}
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if ((res == poly1) || (res == poly2))
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{
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fmpz *t = _fmpz_vec_init(lenr);
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if (len1 >= len2)
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_fmpz_mod_poly_mul(t, poly1->coeffs, len1,
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poly2->coeffs, len2, &(res->p));
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else
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_fmpz_mod_poly_mul(t, poly2->coeffs, len2,
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poly1->coeffs, len1, &(res->p));
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_fmpz_vec_clear(res->coeffs, res->alloc);
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res->alloc = lenr;
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res->length = lenr;
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res->coeffs = t;
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}
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else
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{
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fmpz_mod_poly_fit_length(res, lenr);
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if (len1 >= len2)
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_fmpz_mod_poly_mul(res->coeffs, poly1->coeffs, len1,
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poly2->coeffs, len2, &(res->p));
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else
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_fmpz_mod_poly_mul(res->coeffs, poly2->coeffs, len2,
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poly1->coeffs, len1, &(res->p));
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_fmpz_mod_poly_set_length(res, lenr);
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}
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_fmpz_mod_poly_normalise(res);
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}
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