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

57 lines
1.8 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) 2010 William Hart
Copyright (C) 2011 Fredrik Johansson
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "nmod_poly.h"
#include "ulong_extras.h"
void
nmod_poly_deflate(nmod_poly_t result, const nmod_poly_t input, ulong deflation)
{
slong res_length, i;
if (deflation == 0)
{
flint_printf("Exception (nmod_poly_deflate). Division by zero.\n");
abort();
}
if (input->length <= 1 || deflation == 1)
{
nmod_poly_set(result, input);
return;
}
res_length = (input->length - 1) / deflation + 1;
nmod_poly_fit_length(result, res_length);
for (i = 0; i < res_length; i++)
result->coeffs[i] = input->coeffs[i*deflation];
result->length = res_length;
}