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/*=============================================================================
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) 2007 David Howden
Copyright (C) 2007, 2008, 2009, 2010 William Hart
Copyright (C) 2008 Richard Howell-Peak
Copyright (C) 2011 Fredrik Johansson
******************************************************************************/
#include <stdio.h>
#include <gmp.h>
#include <math.h>
#include "flint.h"
#include "nmod_poly.h"
#include "ulong_extras.h"
#define ZASSENHAUS 0
#define BERLEKAMP 1
#define KALTOFEN 2
static __inline__ void
__nmod_poly_factor1(nmod_poly_factor_t res, const nmod_poly_t f, int algorithm)
{
if (algorithm == KALTOFEN)
nmod_poly_factor_kaltofen_shoup(res, f);
else if (algorithm == ZASSENHAUS)
nmod_poly_factor_cantor_zassenhaus(res, f);
else
nmod_poly_factor_berlekamp(res, f);
}
mp_limb_t
__nmod_poly_factor(nmod_poly_factor_t result,
const nmod_poly_t input, int algorithm)
{
nmod_poly_t monic_input;
nmod_poly_factor_t sqfree_factors, factors;
mp_limb_t leading_coeff;
slong i, len;
len = input->length;
if (len <= 1)
{
if (len == 0)
return 0;
else
return input->coeffs[0];
}
leading_coeff = *nmod_poly_lead(input);
nmod_poly_init_preinv(monic_input, input->mod.n, input->mod.ninv);
nmod_poly_make_monic(monic_input, input);
if (len == 2)
{
nmod_poly_factor_insert(result, monic_input, 1);
nmod_poly_clear(monic_input);
return input->coeffs[1];
}
nmod_poly_factor_init(sqfree_factors);
nmod_poly_factor_squarefree(sqfree_factors, monic_input);
nmod_poly_clear(monic_input);
/* Run CZ on each of the square-free factors */
for (i = 0; i < sqfree_factors->num; i++)
{
nmod_poly_factor_init(factors);
__nmod_poly_factor1(factors, sqfree_factors->p + i, algorithm);
nmod_poly_factor_pow(factors, sqfree_factors->exp[i]);
nmod_poly_factor_concat(result, factors);
nmod_poly_factor_clear(factors);
}
nmod_poly_factor_clear(sqfree_factors);
return leading_coeff;
}
mp_limb_t
__nmod_poly_factor_deflation(nmod_poly_factor_t result,
const nmod_poly_t input, int algorithm)
{
slong i;
ulong deflation;
if (input->length <= 1)
{
if (input->length == 0)
return 0;
else
return input->coeffs[0];
}
deflation = nmod_poly_deflation(input);
if (deflation == 1)
{
return __nmod_poly_factor(result, input, algorithm);
}
else
{
nmod_poly_factor_t def_res;
nmod_poly_t def;
mp_limb_t leading_coeff;
nmod_poly_init_preinv(def, input->mod.n, input->mod.ninv);
nmod_poly_deflate(def, input, deflation);
nmod_poly_factor_init(def_res);
leading_coeff = __nmod_poly_factor(def_res, def, algorithm);
nmod_poly_clear(def);
for (i = 0; i < def_res->num; i++)
{
/* Inflate */
nmod_poly_t pol;
nmod_poly_init_preinv(pol, input->mod.n, input->mod.ninv);
nmod_poly_inflate(pol, def_res->p + i, deflation);
/* Factor inflation */
if (def_res->exp[i] == 1)
__nmod_poly_factor(result, pol, algorithm);
else
{
nmod_poly_factor_t t;
nmod_poly_factor_init(t);
__nmod_poly_factor(t, pol, algorithm);
nmod_poly_factor_pow(t, def_res->exp[i]);
nmod_poly_factor_concat(result, t);
nmod_poly_factor_clear(t);
}
nmod_poly_clear(pol);
}
nmod_poly_factor_clear(def_res);
return leading_coeff;
}
}
mp_limb_t
nmod_poly_factor_with_berlekamp(nmod_poly_factor_t result,
const nmod_poly_t input)
{
return __nmod_poly_factor_deflation(result, input, BERLEKAMP);
}
mp_limb_t
nmod_poly_factor_with_cantor_zassenhaus(nmod_poly_factor_t result,
const nmod_poly_t input)
{
return __nmod_poly_factor_deflation(result, input, ZASSENHAUS);
}
mp_limb_t
nmod_poly_factor_with_kaltofen_shoup(nmod_poly_factor_t result,
const nmod_poly_t input)
{
return __nmod_poly_factor_deflation(result, input, KALTOFEN);
}
mp_limb_t
nmod_poly_factor(nmod_poly_factor_t result, const nmod_poly_t input)
{
mp_limb_t p = input->mod.n;
unsigned int bits = FLINT_BIT_COUNT (p);
slong n = nmod_poly_degree(input);
if (n < 10 + 50 / bits)
return __nmod_poly_factor_deflation(result, input, ZASSENHAUS);
else
return __nmod_poly_factor_deflation(result, input, KALTOFEN);
}
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