115 lines
3.2 KiB
C
115 lines
3.2 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 "fmpz_poly.h"
|
|
|
|
slong _fmpz_poly_hensel_continue_lift(fmpz_poly_factor_t lifted_fac,
|
|
slong *link, fmpz_poly_t *v, fmpz_poly_t *w, const fmpz_poly_t f,
|
|
slong prev, slong curr, slong N, const fmpz_t p)
|
|
{
|
|
const slong r = lifted_fac->num;
|
|
|
|
slong i, new_prev;
|
|
|
|
fmpz_t P;
|
|
fmpz_poly_t monic_f;
|
|
|
|
fmpz_init(P);
|
|
fmpz_pow_ui(P, p, N);
|
|
fmpz_poly_init(monic_f);
|
|
|
|
if (fmpz_is_one(fmpz_poly_lead(f)))
|
|
{
|
|
fmpz_poly_set(monic_f, f);
|
|
}
|
|
else if (fmpz_cmp_si(fmpz_poly_lead(f), -1) == 0)
|
|
{
|
|
fmpz_poly_neg(monic_f, f);
|
|
}
|
|
else
|
|
{
|
|
fmpz_t t;
|
|
|
|
fmpz_init(t);
|
|
fmpz_mod(t, fmpz_poly_lead(f), P);
|
|
|
|
if (fmpz_invmod(t, t, P) == 0)
|
|
{
|
|
flint_printf("Exception (fmpz_poly_continue_hensel_lift).\n");
|
|
abort();
|
|
}
|
|
|
|
fmpz_poly_scalar_mul_fmpz(monic_f, f, t);
|
|
fmpz_poly_scalar_mod_fmpz(monic_f, monic_f, P);
|
|
fmpz_clear(t);
|
|
}
|
|
|
|
{
|
|
slong *e, n = 3 + FLINT_FLOG2(N - prev);
|
|
|
|
e = flint_malloc(n * sizeof(slong));
|
|
|
|
for (e[i = 0] = N; e[i] > curr; i++)
|
|
e[i + 1] = (e[i] + 1) / 2;
|
|
e[i] = curr;
|
|
e[i+1] = prev;
|
|
|
|
if (prev < curr)
|
|
fmpz_poly_hensel_lift_tree(link, v, w, monic_f, r, p, e[i+1], e[i], -1);
|
|
|
|
for (i--; i > 0; i--)
|
|
fmpz_poly_hensel_lift_tree(link, v, w, monic_f, r, p, e[i+1], e[i], 1);
|
|
|
|
fmpz_poly_hensel_lift_tree(link, v, w, monic_f, r, p, e[i+1], e[i], 0);
|
|
|
|
new_prev = e[i+1];
|
|
|
|
flint_free(e);
|
|
}
|
|
|
|
/*
|
|
Now everything is lifted to p^N, we just need to
|
|
insert the factors into their correct places in lifted_fac.
|
|
*/
|
|
fmpz_poly_factor_fit_length(lifted_fac, r);
|
|
|
|
for(i = 0; i < 2*r - 2; i++)
|
|
{
|
|
if (link[i] < 0)
|
|
{
|
|
fmpz_poly_scalar_smod_fmpz(lifted_fac->p + (- link[i] - 1), v[i], P);
|
|
lifted_fac->exp[- link[i] - 1] = WORD(1);
|
|
}
|
|
}
|
|
lifted_fac->num = r;
|
|
|
|
fmpz_clear(P);
|
|
fmpz_poly_clear(monic_f);
|
|
|
|
return new_prev;
|
|
}
|
|
|