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/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2011 Sebastian Pancratz
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_poly.h"
void _fmpz_poly_lcm(fmpz * res, const fmpz * poly1, slong len1,
const fmpz * poly2, slong len2)
{
fmpz *W;
slong lenW = len2;
W = _fmpz_vec_init(len2);
_fmpz_poly_mul(res, poly1, len1, poly2, len2);
_fmpz_poly_gcd(W, poly1, len1, poly2, len2);
FMPZ_VEC_NORM(W, lenW);
if (lenW == 1)
{
if (fmpz_sgn(res + (len1 + len2 - 1 - 1)) < 0)
fmpz_neg(W + 0, W + 0);
_fmpz_vec_scalar_divexact_fmpz(res, res, len1 + len2 - 1, W + 0);
}
else
{
fmpz *V;
slong lenV = len1 + len2 - lenW;
V = _fmpz_vec_init(lenV);
_fmpz_poly_div(V, res, len1 + len2 - 1, W, lenW);
if (fmpz_sgn(V + (lenV - 1)) > 0)
_fmpz_vec_set(res, V, lenV);
else
_fmpz_vec_neg(res, V, lenV);
_fmpz_vec_zero(res + lenV, len1 + len2 - 1 - lenV);
_fmpz_vec_clear(V, lenV);
}
_fmpz_vec_clear(W, len2);
}
void fmpz_poly_lcm(fmpz_poly_t res, const fmpz_poly_t poly1,
const fmpz_poly_t poly2)
{
slong len1 = poly1->length;
slong len2 = poly2->length;
if (len1 == 0 || len2 == 0)
{
fmpz_poly_zero(res);
return;
}
if (res == poly1 || res == poly2)
{
fmpz_poly_t t;
fmpz_poly_init(t);
fmpz_poly_lcm(t, poly1, poly2);
fmpz_poly_swap(res, t);
fmpz_poly_clear(t);
return;
}
fmpz_poly_fit_length(res, len1 + len2 - 1);
_fmpz_poly_set_length(res, len1 + len2 - 1);
if (len1 >= len2)
{
_fmpz_poly_lcm(res->coeffs, poly1->coeffs, len1, poly2->coeffs, len2);
}
else
{
_fmpz_poly_lcm(res->coeffs, poly2->coeffs, len2, poly1->coeffs, len1);
}
_fmpz_poly_normalise(res);
}
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