129 lines
3.3 KiB
C
129 lines
3.3 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) 2011 Andy Novocin
|
|
Copyright (C) 2011 Sebastian Pancratz
|
|
|
|
******************************************************************************/
|
|
|
|
#include <gmp.h>
|
|
#include "flint.h"
|
|
#include "fmpz.h"
|
|
#include "fmpz_poly.h"
|
|
|
|
void fmpz_poly_hensel_build_tree(slong *link, fmpz_poly_t *v, fmpz_poly_t *w,
|
|
const nmod_poly_factor_t fac)
|
|
{
|
|
const slong r = fac->num;
|
|
const nmod_t mod = (fac->p + 0)->mod;
|
|
|
|
slong i, j;
|
|
|
|
nmod_poly_t d;
|
|
nmod_poly_t *V = flint_malloc((2*r - 2)*sizeof(nmod_poly_t));
|
|
nmod_poly_t *W = flint_malloc((2*r - 2)*sizeof(nmod_poly_t));
|
|
|
|
nmod_poly_init_preinv(d, mod.n, mod.ninv);
|
|
|
|
for (i = 0; i < 2*r - 2; i++)
|
|
{
|
|
nmod_poly_init_preinv(V[i], mod.n, mod.ninv);
|
|
nmod_poly_init_preinv(W[i], mod.n, mod.ninv);
|
|
}
|
|
|
|
for (i = 0; i < r; i++)
|
|
{
|
|
nmod_poly_set(V[i], fac->p + i);
|
|
link[i] = - i - 1;
|
|
}
|
|
|
|
for (i = r, j = 0; j < 2*r - 4; i++, j += 2)
|
|
{
|
|
slong s;
|
|
slong minp, mind;
|
|
slong tmp;
|
|
|
|
minp = j;
|
|
mind = nmod_poly_degree(V[j]);
|
|
for (s = j+1; s < i; s++)
|
|
{
|
|
if (nmod_poly_degree(V[s]) < mind)
|
|
{
|
|
minp = s;
|
|
mind = nmod_poly_degree(V[s]);
|
|
}
|
|
}
|
|
|
|
nmod_poly_swap(V[j], V[minp]);
|
|
|
|
/* Swap link[j] and V[minp] */
|
|
tmp = link[j];
|
|
link[j] = link[minp];
|
|
link[minp] = tmp;
|
|
|
|
minp = j+1;
|
|
mind = nmod_poly_degree(V[j+1]);
|
|
|
|
for (s = j + 2; s < i; s++)
|
|
{
|
|
if (nmod_poly_degree(V[s]) < mind)
|
|
{
|
|
minp = s;
|
|
mind = nmod_poly_degree(V[s]);
|
|
}
|
|
}
|
|
|
|
nmod_poly_swap(V[j + 1], V[minp]);
|
|
|
|
/* Swap link[j+1] and V[minp] */
|
|
tmp = link[j + 1];
|
|
link[j+1] = link[minp];
|
|
link[minp] = tmp;
|
|
|
|
nmod_poly_mul(V[i], V[j], V[j+1]);
|
|
link[i] = j;
|
|
}
|
|
|
|
for (j = 0; j < 2*r - 2; j += 2)
|
|
{
|
|
/* N.B. d == 1 */
|
|
nmod_poly_xgcd(d, W[j], W[j+1], V[j], V[j+1]);
|
|
}
|
|
|
|
for (j = 0; j < 2*r - 2; j++)
|
|
{
|
|
fmpz_poly_set_nmod_poly(v[j], V[j]);
|
|
fmpz_poly_set_nmod_poly(w[j], W[j]);
|
|
}
|
|
|
|
for (i = 0; i < 2*r - 2; i++)
|
|
{
|
|
nmod_poly_clear(V[i]);
|
|
nmod_poly_clear(W[i]);
|
|
}
|
|
|
|
nmod_poly_clear(d);
|
|
flint_free(V);
|
|
flint_free(W);
|
|
}
|
|
|