pqc/external/flint-2.4.3/nmod_poly/exp_series_monomial_ui.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
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_monomial_ui(mp_ptr res, mp_limb_t coeff, ulong power,
slong n, nmod_t mod)
{
slong k, r;
mp_limb_t rfac;
mp_limb_t a;
r = (n - 1) / power;
rfac = n_factorial_mod2_preinv(r, mod.n, mod.ninv);
rfac = n_invmod(rfac, mod.n);
if (power > 1)
_nmod_vec_zero(res, n);
res[0] = UWORD(1);
if (coeff == UWORD(1))
{
a = rfac;
for (k = r; k >= 1; k--)
{
res[k * power] = a;
a = n_mulmod2_preinv(a, k, mod.n, mod.ninv);
}
}
else
{
a = coeff;
for (k = power; k < n; k += power)
{
res[k] = a;
a = n_mulmod2_preinv(a, coeff, mod.n, mod.ninv);
}
a = rfac;
for (k = r; k >= 1; k--)
{
res[k * power] = n_mulmod2_preinv(res[k * power],
a, mod.n, mod.ninv);
a = n_mulmod2_preinv(a, k, mod.n, mod.ninv);
}
}
}
void
nmod_poly_exp_series_monomial_ui(nmod_poly_t res, mp_limb_t coeff,
ulong power, slong n)
{
if (n == 0)
{
nmod_poly_zero(res);
return;
}
if (coeff == UWORD(0))
{
nmod_poly_fit_length(res, 1);
res->coeffs[0] = UWORD(1);
res->length = 1;
return;
}
if (power == 0)
{
flint_printf("Exception (nmod_poly_exp_series_monomial_ui). \n"
"Constant term != 0.\n");
abort();
}
if (coeff != UWORD(1))
coeff = n_mod2_preinv(coeff, res->mod.n, res->mod.ninv);
if (n == 1 || power >= n)
{
nmod_poly_fit_length(res, 1);
res->coeffs[0] = UWORD(1);
res->length = 1;
}
nmod_poly_fit_length(res, n);
_nmod_poly_exp_series_monomial_ui(res->coeffs, coeff, power, n, res->mod);
res->length = n;
_nmod_poly_normalise(res);
}