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/*
Copyright (C) 2020 Daniel Schultz
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "ulong_extras.h"
#include "fmpz.h"
#include "fmpz_poly.h"
ulong _fmpz_poly_deflation(const fmpz* a, slong len)
{
ulong i, coeff, deflation;
if (len <= 1)
return len;
coeff = 1;
while (fmpz_is_zero(a + coeff))
coeff++;
deflation = n_gcd(len - 1, coeff);
while ((deflation > 1) && (coeff + deflation < (ulong) len))
{
for (i = 0; i < deflation - 1; i++)
{
coeff++;
if (!fmpz_is_zero(a + coeff))
deflation = n_gcd(coeff, deflation);
}
if (i == deflation - 1)
coeff++;
}
return deflation;
}