116 lines
3.4 KiB
C
116 lines
3.4 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) 2010 Sebastian Pancratz
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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_vec.h"
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#include "fmpz_poly.h"
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#include "fmpq_poly.h"
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void _fmpq_poly_mul(fmpz * rpoly, fmpz_t rden,
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const fmpz * poly1, const fmpz_t den1, slong len1,
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const fmpz * poly2, const fmpz_t den2, slong len2)
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{
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fmpz_t gcd1; /* GCD( poly1, den2 ) */
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fmpz_t gcd2; /* GCD( poly2, den1 ) */
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fmpz_init(gcd1);
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fmpz_init(gcd2);
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fmpz_one(gcd1);
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fmpz_one(gcd2);
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if (*den2 != WORD(1))
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{
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_fmpz_vec_content(gcd1, poly1, len1);
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if (*gcd1 != WORD(1))
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fmpz_gcd(gcd1, gcd1, den2);
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}
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if (*den1 != WORD(1))
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{
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_fmpz_vec_content(gcd2, poly2, len2);
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if (*gcd2 != WORD(1))
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fmpz_gcd(gcd2, gcd2, den1);
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}
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/*
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TODO: If gcd1 and gcd2 are very large compared to the degrees of
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poly1 and poly2, we might want to create copies of the polynomials
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and divide out the common factors *before* the multiplication.
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*/
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_fmpz_poly_mul(rpoly, poly1, len1, poly2, len2);
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fmpz_mul(rden, den1, den2);
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if ((*gcd1 != WORD(1)) | (*gcd2 != WORD(1)))
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{
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fmpz_t g;
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fmpz_init(g);
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fmpz_mul(g, gcd1, gcd2);
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_fmpz_vec_scalar_divexact_fmpz(rpoly, rpoly, len1 + len2 - 1, g);
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fmpz_divexact(rden, rden, g);
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fmpz_clear(g);
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}
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fmpz_clear(gcd1);
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fmpz_clear(gcd2);
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}
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void fmpq_poly_mul(fmpq_poly_t res, const fmpq_poly_t poly1, const fmpq_poly_t poly2)
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{
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slong len;
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if (poly1->length == 0 || poly2->length == 0)
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{
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fmpq_poly_zero(res);
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return;
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}
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len = poly1->length + poly2->length - 1;
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if (res == poly2 || res == poly1)
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{
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fmpq_poly_t t;
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fmpq_poly_init2(t, len);
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fmpq_poly_mul(t, poly1, poly2);
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fmpq_poly_swap(res, t);
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fmpq_poly_clear(t);
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return;
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}
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fmpq_poly_fit_length(res, len);
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if (poly1->length >= poly2->length)
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_fmpq_poly_mul(res->coeffs, res->den,
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poly1->coeffs, poly1->den, poly1->length,
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poly2->coeffs, poly2->den, poly2->length);
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else
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_fmpq_poly_mul(res->coeffs, res->den,
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poly2->coeffs, poly2->den, poly2->length,
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poly1->coeffs, poly1->den, poly1->length);
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_fmpq_poly_set_length(res, len);
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}
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