216 lines
6.1 KiB
C
216 lines
6.1 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, 2011 Sebastian Pancratz
|
|
Copyright (C) 2010 William Hart
|
|
|
|
******************************************************************************/
|
|
|
|
#include <stdlib.h>
|
|
#include <gmp.h>
|
|
#include "flint.h"
|
|
#include "nmod_vec.h"
|
|
#include "nmod_poly.h"
|
|
|
|
/*
|
|
See fmpz_poly/compose_divconquer.c
|
|
*/
|
|
|
|
void
|
|
_nmod_poly_compose_series_divconquer(mp_ptr res, mp_srcptr poly1, slong len1,
|
|
mp_srcptr poly2, slong len2,
|
|
slong N, nmod_t mod)
|
|
{
|
|
slong i, j, k, n;
|
|
slong *hlen, alloc, powlen;
|
|
mp_ptr v, *h, pow, temp;
|
|
|
|
if (len1 == 1)
|
|
{
|
|
res[0] = poly1[0];
|
|
return;
|
|
}
|
|
if (len2 == 1)
|
|
{
|
|
res[0] = _nmod_poly_evaluate_nmod(poly1, len1, poly2[0], mod);
|
|
return;
|
|
}
|
|
if (len1 == 2)
|
|
{
|
|
mp_limb_t t = poly1[0];
|
|
_nmod_vec_scalar_mul_nmod(res, poly2, len2, poly1[1], mod);
|
|
res[0] = n_addmod(res[0], t, mod.n);
|
|
return;
|
|
|
|
}
|
|
|
|
/* Initialisation */
|
|
|
|
hlen = (slong *) flint_malloc(((len1 + 1) / 2) * sizeof(slong));
|
|
|
|
for (k = 1; (2 << k) < len1; k++) ;
|
|
|
|
hlen[0] = hlen[1] = FLINT_MIN(N, ((1 << k) - 1) * (len2 - 1) + 1);
|
|
for (i = k - 1; i > 0; i--)
|
|
{
|
|
slong hi = (len1 + (1 << i) - 1) / (1 << i);
|
|
slong t = FLINT_MIN(N, ((1 << i) - 1) * (len2 - 1) + 1);
|
|
for (n = (hi + 1) / 2; n < hi; n++)
|
|
hlen[n] = t;
|
|
}
|
|
powlen = FLINT_MIN(N, (1 << k) * (len2 - 1) + 1);
|
|
|
|
alloc = 0;
|
|
for (i = 0; i < (len1 + 1) / 2; i++)
|
|
alloc += hlen[i];
|
|
|
|
v = _nmod_vec_init(alloc + 2 * powlen);
|
|
h = (mp_ptr *) flint_malloc(((len1 + 1) / 2) * sizeof(mp_ptr));
|
|
h[0] = v;
|
|
for (i = 0; i < (len1 - 1) / 2; i++)
|
|
{
|
|
h[i + 1] = h[i] + hlen[i];
|
|
hlen[i] = 0;
|
|
}
|
|
hlen[(len1 - 1) / 2] = 0;
|
|
pow = v + alloc;
|
|
temp = pow + powlen;
|
|
|
|
/* Let's start the actual work */
|
|
|
|
for (i = 0, j = 0; i < len1 / 2; i++, j += 2)
|
|
{
|
|
if (poly1[j + 1] != WORD(0))
|
|
{
|
|
_nmod_vec_scalar_mul_nmod(h[i], poly2, len2, poly1[j + 1], mod);
|
|
h[i][0] = n_addmod(h[i][0], poly1[j], mod.n);
|
|
hlen[i] = len2;
|
|
}
|
|
else if (poly1[j] != WORD(0))
|
|
{
|
|
h[i][0] = poly1[j];
|
|
hlen[i] = 1;
|
|
}
|
|
}
|
|
if ((len1 & WORD(1)))
|
|
{
|
|
if (poly1[j] != WORD(0))
|
|
{
|
|
h[i][0] = poly1[j];
|
|
hlen[i] = 1;
|
|
}
|
|
}
|
|
|
|
powlen = FLINT_MIN(N, 2 * len2 - 1);
|
|
_nmod_poly_mullow(pow, poly2, len2, poly2, len2, powlen, mod);
|
|
|
|
for (n = (len1 + 1) / 2; n > 2; n = (n + 1) / 2)
|
|
{
|
|
if (hlen[1] > 0)
|
|
{
|
|
slong templen = FLINT_MIN(N, powlen + hlen[1] - 1);
|
|
_nmod_poly_mullow(temp, pow, powlen, h[1], hlen[1], templen, mod);
|
|
_nmod_poly_add(h[0], temp, templen, h[0], hlen[0], mod);
|
|
hlen[0] = FLINT_MAX(hlen[0], templen);
|
|
}
|
|
|
|
for (i = 1; i < n / 2; i++)
|
|
{
|
|
if (hlen[2*i + 1] > 0)
|
|
{
|
|
hlen[i] = FLINT_MIN(N, hlen[2*i + 1] + powlen - 1);
|
|
_nmod_poly_mullow(h[i], pow, powlen, h[2*i + 1], hlen[2*i + 1],
|
|
hlen[i], mod);
|
|
}
|
|
else
|
|
{
|
|
hlen[i] = 0;
|
|
}
|
|
_nmod_poly_add(h[i], h[i], hlen[i], h[2*i], hlen[2*i], mod);
|
|
hlen[i] = FLINT_MAX(hlen[i], hlen[2*i]);
|
|
}
|
|
if ((n & WORD(1)))
|
|
{
|
|
hlen[i] = FLINT_MIN(N, hlen[2*i]);
|
|
flint_mpn_copyi(h[i], h[2*i], hlen[i]);
|
|
}
|
|
|
|
_nmod_poly_mullow(temp, pow, powlen, pow, powlen,
|
|
FLINT_MIN(N, 2 * powlen - 1), mod);
|
|
powlen = FLINT_MIN(N, 2 * powlen - 1);
|
|
{
|
|
mp_ptr t = pow;
|
|
pow = temp;
|
|
temp = t;
|
|
}
|
|
}
|
|
|
|
_nmod_poly_mullow(res, pow, powlen, h[1], hlen[1],
|
|
FLINT_MIN(N, powlen + hlen[1] - 1), mod);
|
|
_nmod_vec_add(res, res, h[0], hlen[0], mod);
|
|
|
|
_nmod_vec_clear(v);
|
|
flint_free(h);
|
|
flint_free(hlen);
|
|
}
|
|
|
|
void
|
|
nmod_poly_compose_series_divconquer(nmod_poly_t res,
|
|
const nmod_poly_t poly1, const nmod_poly_t poly2, slong N)
|
|
{
|
|
const slong len1 = poly1->length;
|
|
const slong len2 = FLINT_MIN(N, poly2->length);
|
|
slong lenr;
|
|
|
|
if (len1 == 0 || N == 0)
|
|
{
|
|
nmod_poly_zero(res);
|
|
return;
|
|
}
|
|
if (len1 == 1 || len2 == 0)
|
|
{
|
|
nmod_poly_set_coeff_ui(res, 0, poly1->coeffs[0]);
|
|
nmod_poly_truncate(res, 1);
|
|
return;
|
|
}
|
|
|
|
lenr = FLINT_MIN(N, (len1 - 1) * (len2 - 1) + 1);
|
|
|
|
if (res != poly1 && res != poly2)
|
|
{
|
|
nmod_poly_fit_length(res, lenr);
|
|
_nmod_poly_compose_series_divconquer(res->coeffs,
|
|
poly1->coeffs, len1, poly2->coeffs, len2, N, poly1->mod);
|
|
}
|
|
else
|
|
{
|
|
nmod_poly_t t;
|
|
nmod_poly_init2(t, poly1->mod.n, lenr);
|
|
_nmod_poly_compose_series_divconquer(t->coeffs,
|
|
poly1->coeffs, len1, poly2->coeffs, len2, N, poly1->mod);
|
|
nmod_poly_swap(res, t);
|
|
nmod_poly_clear(t);
|
|
}
|
|
|
|
res->length = lenr;
|
|
_nmod_poly_normalise(res);
|
|
}
|