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/*
Copyright (C) 2011 Andy Novocin
Copyright (C) 2011 Sebastian Pancratz
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpz.h"
#include "fmpz_poly.h"
#include "fmpz_poly_factor.h"
void fmpz_poly_factor_squarefree(fmpz_poly_factor_t fac, const fmpz_poly_t F)
{
fmpz_poly_content(&(fac->c), F);
if (F->length != 0 && fmpz_sgn(fmpz_poly_lead(F)) < 0)
fmpz_neg(&(fac->c), &(fac->c));
if (F->length > 1)
{
fmpz_poly_t f, d, t1;
fmpz_poly_init(f);
fmpz_poly_init(d);
fmpz_poly_init(t1);
fmpz_poly_scalar_divexact_fmpz(f, F, &(fac->c));
fmpz_poly_derivative(t1, f);
fmpz_poly_gcd(d, f, t1);
if (d->length == 1)
{
fmpz_poly_factor_insert(fac, f, 1);
}
else
{
fmpz_poly_t v, w, s;
slong i;
fmpz_poly_init(v);
fmpz_poly_init(w);
fmpz_poly_init(s);
fmpz_poly_divexact(v, f, d);
fmpz_poly_divexact(w, t1, d);
for (i = 1; ; i++)
{
fmpz_poly_derivative(t1, v);
fmpz_poly_sub(s, w, t1);
if (s->length == 0)
{
if (v->length > 1)
fmpz_poly_factor_insert(fac, v, i);
break;
}
fmpz_poly_gcd(d, v, s);
fmpz_poly_divexact(v, v, d);
fmpz_poly_divexact(w, s, d);
if (d->length > 1)
fmpz_poly_factor_insert(fac, d, i);
}
fmpz_poly_clear(v);
fmpz_poly_clear(w);
fmpz_poly_clear(s);
}
fmpz_poly_clear(f);
fmpz_poly_clear(d);
fmpz_poly_clear(t1);
}
}