pqc/external/flint-2.4.3/nmod_poly/div_series.c
2014-05-24 23:16:06 +02:00

110 lines
2.9 KiB
C

/*=============================================================================
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 William Hart
******************************************************************************/
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "nmod_vec.h"
#include "nmod_poly.h"
#include "ulong_extras.h"
void
_nmod_poly_div_series(mp_ptr Q, mp_srcptr A, mp_srcptr B,
slong n, nmod_t mod)
{
mp_ptr Binv = _nmod_vec_init(n);
_nmod_poly_inv_series(Binv, B, n, mod);
_nmod_poly_mullow(Q, Binv, n, A, n, n, mod);
_nmod_vec_clear(Binv);
}
void
nmod_poly_div_series(nmod_poly_t Q, const nmod_poly_t A,
const nmod_poly_t B, slong n)
{
mp_ptr A_coeffs, B_coeffs, Q_coeffs;
nmod_poly_t t1;
slong Alen, Blen;
Blen = B->length;
if (n == 0 || Blen == 0 || B->coeffs[0] == 0)
{
flint_printf("Exception (nmod_poly_div_series). Division by zero.\n");
abort();
}
Alen = A->length;
if (Alen < n)
{
A_coeffs = _nmod_vec_init(n);
flint_mpn_copyi(A_coeffs, A->coeffs, Alen);
flint_mpn_zero(A_coeffs + Alen, n - Alen);
}
else
A_coeffs = A->coeffs;
if (Blen < n)
{
B_coeffs = _nmod_vec_init(n);
flint_mpn_copyi(B_coeffs, B->coeffs, Blen);
flint_mpn_zero(B_coeffs + Blen, n - Blen);
}
else
B_coeffs = B->coeffs;
if ((Q == A || Q == B) && Q->length >= n)
{
nmod_poly_init2(t1, Q->mod.n, n);
Q_coeffs = t1->coeffs;
}
else
{
nmod_poly_fit_length(Q, n);
Q_coeffs = Q->coeffs;
}
_nmod_poly_div_series(Q_coeffs, A_coeffs, B_coeffs, n, Q->mod);
if ((Q == A || Q == B) && Q->length >= n)
{
nmod_poly_swap(Q, t1);
nmod_poly_clear(t1);
}
Q->length = n;
if (Alen < n)
_nmod_vec_clear(A_coeffs);
if (Blen < n)
_nmod_vec_clear(B_coeffs);
_nmod_poly_normalise(Q);
}