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/*
Copyright (C) 2017 Fredrik Johansson
This file is part of Arb.
Arb 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 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "arb_fmpz_poly.h"
ulong arb_fmpz_poly_deflation(const fmpz_poly_t input)
{
slong i, coeff, deflation;
if (input->length <= 1)
return input->length;
coeff = 1;
while (fmpz_is_zero(input->coeffs + coeff))
coeff++;
deflation = n_gcd(input->length - 1, coeff);
while ((deflation > 1) && (coeff + deflation < input->length))
{
for (i = 0; i < deflation - 1; i++)
{
coeff++;
if (!fmpz_is_zero(input->coeffs + coeff))
deflation = n_gcd(coeff, deflation);
}
if (i == deflation - 1)
coeff++;
}
return deflation;
}
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