61 lines
1.8 KiB
C
61 lines
1.8 KiB
C
/*=============================================================================
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This file is part of FLINT.
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FLINT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FLINT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2010 William Hart
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Copyright (C) 2011 Fredrik Johansson
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "nmod_poly.h"
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#include "ulong_extras.h"
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ulong
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nmod_poly_deflation(const nmod_poly_t input)
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{
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ulong deflation;
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slong i, coeff;
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if (input->length <= 1)
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return input->length;
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coeff = 1;
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while (!input->coeffs[coeff])
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coeff++;
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deflation = n_gcd_full(input->length - 1, coeff);
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while ((deflation > 1) && (coeff + deflation < input->length))
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{
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for (i = 0; i < deflation - 1; i++)
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{
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coeff++;
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if (input->coeffs[coeff])
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deflation = n_gcd_full(coeff, deflation);
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}
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if (i == deflation - 1)
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coeff++;
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}
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return deflation;
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}
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