pqc/external/flint-2.4.3/nmod_poly/exp_series_basecase.c
2014-05-24 23:16:06 +02:00

90 lines
2.5 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 <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
#include "nmod_vec.h"
#include "nmod_poly.h"
void
_nmod_poly_exp_series_basecase(mp_ptr f, mp_srcptr h,
slong hlen, slong n, nmod_t mod)
{
slong j, k;
mp_ptr a;
mp_limb_t s;
f[0] = UWORD(1);
a = _nmod_vec_init(FLINT_MIN(n, hlen));
for (k = 1; k < FLINT_MIN(n, hlen); k++)
a[k] = n_mulmod2_preinv(h[k], k, mod.n, mod.ninv);
for (k = 1; k < n; k++)
{
s = n_mulmod2_preinv(a[1], f[k-1], mod.n, mod.ninv);
for (j = 2; j < FLINT_MIN(k + 1, hlen); j++)
NMOD_ADDMUL(s, a[j], f[k - j], mod);
f[k] = n_mulmod2_preinv(s, n_invmod(k, mod.n), mod.n, mod.ninv);
}
_nmod_vec_clear(a);
}
void
nmod_poly_exp_series_basecase(nmod_poly_t f, const nmod_poly_t h, slong n)
{
slong hlen;
nmod_poly_fit_length(f, n);
hlen = h->length;
if (hlen > 0 && h->coeffs[0] != UWORD(0))
{
flint_printf("Exception (nmod_poly_exp_series_basecase). Constant term != 0.\n");
abort();
}
if (n <= 1 || hlen == 0)
{
if (n == 0)
{
nmod_poly_zero(f);
}
else
{
f->coeffs[0] = UWORD(1);
f->length = 1;
}
return;
}
_nmod_poly_exp_series_basecase(f->coeffs, h->coeffs, hlen, n, f->mod);
f->length = n;
_nmod_poly_normalise(f);
}