80 lines
2.4 KiB
C
80 lines
2.4 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 Fredrik Johansson
|
|
|
|
******************************************************************************/
|
|
|
|
#include "nmod_poly.h"
|
|
#include "ulong_extras.h"
|
|
|
|
void
|
|
_nmod_poly_product_roots_nmod_vec(mp_ptr poly, mp_srcptr xs, slong n, nmod_t mod)
|
|
{
|
|
if (n == 0)
|
|
{
|
|
poly[0] = UWORD(1);
|
|
}
|
|
else if (n < 20)
|
|
{
|
|
slong i, j;
|
|
|
|
poly[n] = UWORD(1);
|
|
poly[n - 1] = nmod_neg(xs[0], mod);
|
|
|
|
for (i = 1; i < n; i++)
|
|
{
|
|
poly[n-i-1] = nmod_neg(n_mulmod2_preinv(poly[n-i], xs[i],
|
|
mod.n, mod.ninv), mod);
|
|
|
|
for (j = 0; j < i - 1; j++)
|
|
{
|
|
poly[n-i+j] = nmod_sub(poly[n-i+j],
|
|
n_mulmod2_preinv(poly[n-i+j+1], xs[i], mod.n, mod.ninv),
|
|
mod);
|
|
}
|
|
|
|
poly[n-1] = nmod_sub(poly[n-1], xs[i], mod);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
const slong m = (n + 1) / 2;
|
|
mp_ptr tmp;
|
|
|
|
tmp = _nmod_vec_init(n + 2);
|
|
|
|
_nmod_poly_product_roots_nmod_vec(tmp, xs, m, mod);
|
|
_nmod_poly_product_roots_nmod_vec(tmp + m + 1, xs + m, n - m, mod);
|
|
_nmod_poly_mul(poly, tmp, m + 1, tmp + m + 1, n - m + 1, mod);
|
|
|
|
_nmod_vec_clear(tmp);
|
|
}
|
|
}
|
|
|
|
void
|
|
nmod_poly_product_roots_nmod_vec(nmod_poly_t poly, mp_srcptr xs, slong n)
|
|
{
|
|
nmod_poly_fit_length(poly, n + 1);
|
|
_nmod_poly_product_roots_nmod_vec(poly->coeffs, xs, n, poly->mod);
|
|
poly->length = n + 1;
|
|
}
|