pqc/external/flint-2.4.3/fmpz_mod_poly/derivative.c

71 lines
2.1 KiB
C
Raw Normal View History

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 Sebastian Pancratz
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_poly.h"
#include "fmpz_mod_poly.h"
void _fmpz_mod_poly_derivative(fmpz *res, const fmpz *poly, slong len,
const fmpz_t p)
{
slong j, k = 1;
for (j = 1; j < len; j++)
{
if (k == 0)
fmpz_zero(res + (j - 1));
else if (k == 1)
fmpz_set(res + (j - 1), poly + j);
else
{
fmpz_mul_ui(res + (j - 1), poly + j, k);
fmpz_mod(res + (j - 1), res + (j - 1), p);
}
if (fmpz_equal_ui(p, ++k))
k = 0;
}
}
void fmpz_mod_poly_derivative(fmpz_mod_poly_t res, const fmpz_mod_poly_t poly)
{
const slong len = poly->length;
if (len < 2)
{
fmpz_mod_poly_zero(res);
}
else
{
fmpz_mod_poly_fit_length(res, len - 1);
_fmpz_mod_poly_derivative(res->coeffs, poly->coeffs, len, &(res->p));
_fmpz_mod_poly_set_length(res, len - 1);
_fmpz_mod_poly_normalise(res);
}
}