pqc/external/flint-2.4.3/fmpq_poly/tan_series.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) 2010 Sebastian Pancratz
Copyright (C) 2011 Fredrik Johansson
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpq_poly.h"
void
_fmpq_poly_tan_series(fmpz * g, fmpz_t gden,
const fmpz * h, const fmpz_t hden, slong n)
{
slong m;
fmpz * t, * u, * v;
fmpz_t tden, uden, vden;
if (n <= 3)
{
if (n >= 1) fmpz_set(g + 0, h + 0);
if (n >= 2) fmpz_set(g + 1, h + 1);
if (n == 3) fmpz_set(g + 2, h + 2);
fmpz_set(gden, hden);
_fmpq_poly_canonicalise(g, gden, n);
return;
}
m = (n + 1) / 2;
_fmpq_poly_tan_series(g, gden, h, hden, m);
_fmpz_vec_zero(g + m, n - m);
t = _fmpz_vec_init(n);
u = _fmpz_vec_init(n);
v = _fmpz_vec_init(n);
fmpz_init(tden);
fmpz_init(uden);
fmpz_init(vden);
_fmpq_poly_mul(u, uden, g, gden, m, g, gden, m);
fmpz_set(u, uden); /* u += 1 */
if (2*m - 1 < n)
fmpz_zero(u + n - 1);
_fmpq_poly_atan_series(t, tden, g, gden, n);
_fmpq_poly_sub(t, tden, t, tden, n, h, hden, n);
_fmpq_poly_mullow(v + m, vden, u, uden, n, t + m, tden, n - m, n - m);
_fmpq_poly_sub(g, gden, g, gden, m, v, vden, n);
_fmpq_poly_canonicalise(g, gden, n);
fmpz_clear(tden);
fmpz_clear(uden);
fmpz_clear(vden);
_fmpz_vec_clear(t, n);
_fmpz_vec_clear(u, n);
_fmpz_vec_clear(v, n);
}
void fmpq_poly_tan_series(fmpq_poly_t res, const fmpq_poly_t poly, slong n)
{
fmpz *copy;
int alloc;
if (poly->length == 0)
{
fmpq_poly_zero(res);
return;
}
if (!fmpz_is_zero(poly->coeffs))
{
flint_printf("Exception (fmpq_poly_tan_series). Constant term != 0.\n");
abort();
}
if (n < 2)
{
fmpq_poly_zero(res);
return;
}
if (poly->length >= n)
{
copy = poly->coeffs;
alloc = 0;
}
else
{
slong i;
copy = (fmpz *) flint_malloc(n * sizeof(fmpz));
for (i = 0; i < poly->length; i++)
copy[i] = poly->coeffs[i];
for ( ; i < n; i++)
copy[i] = 0;
alloc = 1;
}
if (res != poly)
{
fmpq_poly_fit_length(res, n);
_fmpq_poly_tan_series(res->coeffs, res->den, copy, poly->den, n);
}
else
{
fmpq_poly_t t;
fmpq_poly_init2(t, n);
_fmpq_poly_tan_series(t->coeffs, t->den, copy, poly->den, n);
fmpq_poly_swap(res, t);
fmpq_poly_clear(t);
}
_fmpq_poly_set_length(res, n);
_fmpq_poly_normalise(res);
if (alloc)
flint_free(copy);
}