pqc/external/flint-2.4.3/fmpq_poly/rem_powers_precomp.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) 2013 William Hart
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_poly.h"
#include "fmpq_poly.h"
void _fmpq_poly_rem_powers_precomp(fmpz * A, fmpz_t denA, slong m,
const fmpz * B, const fmpz_t denB, slong n,
fmpq_poly_struct * const powers)
{
slong i;
fmpq_poly_t prod;
fmpz_t den;
if (m >= 2*n) /* TODO: make this case use the precomputed squares */
{
fmpz * R = _fmpz_vec_init(m);
fmpz_init(den);
_fmpz_vec_set(R, A, m);
fmpz_set(den, denA);
_fmpq_poly_rem(A, denA, R, den, m, B, denB, n, NULL);
_fmpz_vec_clear(R, m);
fmpz_clear(den);
return;
}
if (m < n)
return;
fmpz_init(den);
fmpq_poly_init2(prod, n - 1);
fmpz_set(den, denA);
for (i = n - 1; i < m; i++)
{
_fmpz_vec_scalar_mul_fmpz(fmpq_poly_numref(prod),
fmpq_poly_numref(powers + i), powers[i].length, A + i);
fmpz_mul(fmpq_poly_denref(prod), fmpq_poly_denref(powers + i), den);
_fmpq_poly_add_can(A, denA, A, denA, n - 1, fmpq_poly_numref(prod),
fmpq_poly_denref(prod), powers[i].length, 0);
}
fmpq_poly_clear(prod);
fmpz_clear(den);
}
void
fmpq_poly_rem_powers_precomp(fmpq_poly_t R, const fmpq_poly_t A,
const fmpq_poly_t B, const fmpq_poly_powers_precomp_t B_inv)
{
fmpq_poly_t tR;
fmpz * r, * d;
slong len1 = A->length, len2 = B->length;
if (len1 < len2)
{
fmpq_poly_set(R, A);
return;
}
if (R == B)
{
fmpq_poly_init2(tR, len1);
r = fmpq_poly_numref(tR);
d = fmpq_poly_denref(tR);
}
else
{
fmpq_poly_fit_length(R, len1);
r = fmpq_poly_numref(R);
d = fmpq_poly_denref(R);
}
if (R == B || R != A)
{
_fmpz_vec_set(r, fmpq_poly_numref(A), len1);
fmpz_set(d, fmpq_poly_denref(A));
}
_fmpq_poly_rem_powers_precomp(r, d, len1, fmpq_poly_numref(B),
fmpq_poly_denref(B), len2, B_inv->powers);
if (R == B)
{
_fmpq_poly_set_length(tR, len2 - 1);
fmpq_poly_swap(tR, R);
fmpq_poly_clear(tR);
}
else
_fmpq_poly_set_length(R, len2 - 1);
_fmpq_poly_normalise(R);
}