106 lines
2.9 KiB
C
106 lines
2.9 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) 2011 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_poly.h"
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void _fmpz_poly_lcm(fmpz * res, const fmpz * poly1, slong len1,
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const fmpz * poly2, slong len2)
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{
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fmpz *W;
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slong lenW = len2;
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W = _fmpz_vec_init(len2);
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_fmpz_poly_mul(res, poly1, len1, poly2, len2);
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_fmpz_poly_gcd(W, poly1, len1, poly2, len2);
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FMPZ_VEC_NORM(W, lenW);
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if (lenW == 1)
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{
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if (fmpz_sgn(res + (len1 + len2 - 1 - 1)) < 0)
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fmpz_neg(W + 0, W + 0);
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_fmpz_vec_scalar_divexact_fmpz(res, res, len1 + len2 - 1, W + 0);
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}
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else
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{
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fmpz *V;
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slong lenV = len1 + len2 - lenW;
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V = _fmpz_vec_init(lenV);
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_fmpz_poly_div(V, res, len1 + len2 - 1, W, lenW);
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if (fmpz_sgn(V + (lenV - 1)) > 0)
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_fmpz_vec_set(res, V, lenV);
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else
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_fmpz_vec_neg(res, V, lenV);
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_fmpz_vec_zero(res + lenV, len1 + len2 - 1 - lenV);
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_fmpz_vec_clear(V, lenV);
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}
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_fmpz_vec_clear(W, len2);
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}
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void fmpz_poly_lcm(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 len1 = poly1->length;
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slong len2 = poly2->length;
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if (len1 == 0 || len2 == 0)
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{
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fmpz_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_poly_t t;
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fmpz_poly_init(t);
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fmpz_poly_lcm(t, poly1, poly2);
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fmpz_poly_swap(res, t);
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fmpz_poly_clear(t);
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return;
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}
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fmpz_poly_fit_length(res, len1 + len2 - 1);
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_fmpz_poly_set_length(res, len1 + len2 - 1);
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if (len1 >= len2)
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{
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_fmpz_poly_lcm(res->coeffs, poly1->coeffs, len1, poly2->coeffs, len2);
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}
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else
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{
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_fmpz_poly_lcm(res->coeffs, poly2->coeffs, len2, poly1->coeffs, len1);
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}
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_fmpz_poly_normalise(res);
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}
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