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/*=============================================================================
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"
ulong
nmod_poly_deflation(const nmod_poly_t input)
{
ulong deflation;
slong i, coeff;
if (input->length <= 1)
return input->length;
coeff = 1;
while (!input->coeffs[coeff])
coeff++;
deflation = n_gcd_full(input->length - 1, coeff);
while ((deflation > 1) && (coeff + deflation < input->length))
{
for (i = 0; i < deflation - 1; i++)
{
coeff++;
if (input->coeffs[coeff])
deflation = n_gcd_full(coeff, deflation);
}
if (i == deflation - 1)
coeff++;
}
return deflation;
}
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