pqc/external/flint-2.4.3/fmpq_poly/lcm.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
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 <stdlib.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpz_poly.h"
#include "fmpq_poly.h"
void _fmpq_poly_lcm(fmpz *L, fmpz_t denL,
const fmpz *A, slong lenA, const fmpz *B, slong lenB)
{
if (lenA == 1) /* lenA == lenB == 1 */
{
fmpz_one(L);
fmpz_one(denL);
}
else
{
fmpz *copyA, *copyB;
fmpz_t s, t;
slong lenL;
fmpz_init(s);
fmpz_init(t);
_fmpz_vec_content(s, A, lenA);
_fmpz_vec_content(t, B, lenB);
if (fmpz_is_one(s))
{
if (fmpz_is_one(t))
{
copyA = (fmpz *) A;
copyB = (fmpz *) B;
}
else
{
copyA = (fmpz *) A;
copyB = _fmpz_vec_init(lenB);
_fmpz_vec_scalar_divexact_fmpz(copyB, B, lenB, t);
}
}
else
{
if (fmpz_is_one(s))
{
copyA = _fmpz_vec_init(lenA);
copyB = (fmpz *) B;
_fmpz_vec_scalar_divexact_fmpz(copyA, A, lenA, s);
}
else
{
copyA = _fmpz_vec_init(lenA + lenB);
copyB = copyA + lenA;
_fmpz_vec_scalar_divexact_fmpz(copyA, A, lenA, s);
_fmpz_vec_scalar_divexact_fmpz(copyB, B, lenB, t);
}
}
_fmpz_poly_lcm(L, copyA, lenA, copyB, lenB);
for (lenL = lenA + lenB - 2; !L[lenL]; lenL--) ;
lenL++;
fmpz_set(denL, L + (lenL - 1));
if (A != copyA)
_fmpz_vec_clear(copyA, lenA + (B != copyB) * lenB);
else if (B != copyB)
_fmpz_vec_clear(copyB, lenB);
fmpz_clear(s);
fmpz_clear(t);
}
}
void fmpq_poly_lcm(fmpq_poly_t L, const fmpq_poly_t A, const fmpq_poly_t B)
{
slong lenA = A->length, lenB = B->length, lenL = lenA + lenB - 1;
if (lenA == 0 || lenB == 0)
{
fmpq_poly_zero(L);
return;
}
if (L == A || L == B)
{
fmpq_poly_t t;
fmpq_poly_init2(t, lenL);
if (lenA >= lenB)
_fmpq_poly_lcm(t->coeffs, t->den, A->coeffs, A->length,
B->coeffs, B->length);
else
_fmpq_poly_lcm(t->coeffs, t->den, B->coeffs, B->length,
A->coeffs, A->length);
fmpq_poly_swap(t, L);
fmpq_poly_clear(t);
}
else
{
fmpq_poly_fit_length(L, lenL);
if (lenA >= lenB)
_fmpq_poly_lcm(L->coeffs, L->den, A->coeffs, A->length,
B->coeffs, B->length);
else
_fmpq_poly_lcm(L->coeffs, L->den, B->coeffs, B->length,
A->coeffs, A->length);
}
_fmpq_poly_set_length(L, lenL);
_fmpq_poly_normalise(L);
}