pqc/external/flint-2.4.3/fmpq_poly/compose_series_horner.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 "fmpz_poly.h"
#include "fmpq_poly.h"
void
_fmpq_poly_compose_series_horner(fmpz * res, fmpz_t den, const fmpz * poly1,
const fmpz_t den1, slong len1, const fmpz * poly2,
const fmpz_t den2, slong len2, slong n)
{
if (fmpz_is_one(den2))
{
_fmpz_poly_compose_series(res, poly1, len1, poly2, len2, n);
fmpz_set(den, den1);
_fmpq_poly_canonicalise(res, den, n);
}
else if (n == 1)
{
fmpz_set(res, poly1);
fmpz_set(den, den1);
_fmpq_poly_canonicalise(res, den, 1);
}
else
{
slong i = len1 - 1;
slong lenr;
fmpz_t tden;
fmpz * t = _fmpz_vec_init(n);
fmpz_init(tden);
_fmpz_vec_zero(res, n);
lenr = len2;
_fmpq_poly_scalar_mul_fmpz(res, den, poly2, den2, len2, poly1 + i);
_fmpq_poly_scalar_div_fmpz(res, den, res, den, len2, den1);
i--;
_fmpq_poly_add(res, den, res, den, len2, poly1 + i, den1, 1);
_fmpq_poly_canonicalise(res, den, lenr);
while (i > 0)
{
i--;
if (lenr + len2 - 1 < n)
{
_fmpq_poly_mul(t, tden, res, den, lenr, poly2, den2, len2);
lenr = lenr + len2 - 1;
}
else
{
_fmpq_poly_mullow(t, tden, res, den, lenr,
poly2, den2, len2, n);
lenr = n;
}
_fmpq_poly_canonicalise(t, tden, lenr);
_fmpq_poly_add(res, den, t, tden, lenr, poly1 + i, den1, 1);
}
_fmpq_poly_canonicalise(res, den, n);
_fmpz_vec_clear(t, n);
fmpz_clear(tden);
}
}
void
fmpq_poly_compose_series_horner(fmpq_poly_t res,
const fmpq_poly_t poly1, const fmpq_poly_t poly2, slong n)
{
slong len1 = poly1->length;
slong len2 = poly2->length;
slong lenr;
if (len2 != 0 && !fmpz_is_zero(poly2->coeffs))
{
flint_printf("Exception (fmpq_poly_compose_series_horner). Inner polynomial \n"
"must have zero constant term.\n");
abort();
}
if (len1 == 0 || n == 0)
{
fmpq_poly_zero(res);
return;
}
if (len2 == 0 || len1 == 1)
{
fmpq_poly_fit_length(res, 1);
fmpz_set(res->coeffs, poly1->coeffs);
fmpz_set(res->den, poly1->den);
{
fmpz_t d;
fmpz_init(d);
fmpz_gcd(d, res->coeffs, res->den);
if (!fmpz_is_one(d))
{
fmpz_divexact(res->coeffs, res->coeffs, d);
fmpz_divexact(res->den, res->den, d);
}
fmpz_clear(d);
}
_fmpq_poly_set_length(res, 1);
_fmpq_poly_normalise(res);
return;
}
lenr = FLINT_MIN((len1 - 1) * (len2 - 1) + 1, n);
len1 = FLINT_MIN(len1, lenr);
len2 = FLINT_MIN(len2, lenr);
if ((res != poly1) && (res != poly2))
{
fmpq_poly_fit_length(res, lenr);
_fmpq_poly_compose_series_horner(res->coeffs, res->den,
poly1->coeffs, poly1->den, len1,
poly2->coeffs, poly2->den, len2, lenr);
_fmpq_poly_set_length(res, lenr);
_fmpq_poly_normalise(res);
}
else
{
fmpq_poly_t t;
fmpq_poly_init2(t, lenr);
_fmpq_poly_compose_series_horner(t->coeffs, t->den,
poly1->coeffs, poly1->den, len1,
poly2->coeffs, poly2->den, len2, lenr);
_fmpq_poly_set_length(t, lenr);
_fmpq_poly_normalise(t);
fmpq_poly_swap(res, t);
fmpq_poly_clear(t);
}
}