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

108 lines
2.8 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) 2010 Sebastian Pancratz
******************************************************************************/
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpz_poly.h"
void
_fmpz_poly_div_series(fmpz * Q, const fmpz * A, const fmpz * B, slong n)
{
if (n == 1)
{
_fmpz_vec_set(Q, A, n);
}
else
{
fmpz * Binv = _fmpz_vec_init(n);
_fmpz_poly_inv_series(Binv, B, n);
_fmpz_poly_mullow(Q, A, n, Binv, n, n);
_fmpz_vec_clear(Binv, n);
}
}
void fmpz_poly_div_series(fmpz_poly_t Q, const fmpz_poly_t A,
const fmpz_poly_t B, slong n)
{
fmpz *a, *b;
ulong flags = UWORD(0); /* 2^0 for a, 2^1 for b */
if (Q == A)
{
fmpz_poly_t t;
fmpz_poly_init2(t, n);
fmpz_poly_div_series(t, A, B, n);
fmpz_poly_swap(Q, t);
fmpz_poly_clear(t);
return;
}
fmpz_poly_fit_length(Q, n);
if (A->length >= n)
{
a = A->coeffs;
}
else
{
slong i;
a = (fmpz *) flint_malloc(n * sizeof(fmpz));
for (i = 0; i < A->length; i++)
a[i] = A->coeffs[i];
flint_mpn_zero((mp_ptr) a + A->length, n - A->length);
flags |= UWORD(1);
}
if (B->length >= n)
{
b = B->coeffs;
}
else
{
slong i;
b = (fmpz *) flint_malloc(n * sizeof(fmpz));
for (i = 0; i < B->length; i++)
b[i] = B->coeffs[i];
flint_mpn_zero((mp_ptr) b + B->length, n - B->length);
flags |= UWORD(2);
}
_fmpz_poly_div_series(Q->coeffs, a, b, n);
_fmpz_poly_set_length(Q, n);
_fmpz_poly_normalise(Q);
if ((flags & UWORD(1)))
flint_free(a);
if ((flags & UWORD(2)))
flint_free(b);
}