63 lines
1.9 KiB
C
63 lines
1.9 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) 2008, 2009 William Hart
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Copyright (C) 2009 Thomas Boothby
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "ulong_extras.h"
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#define FLINT_ONE_LINE_MULTIPLIER 480
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mp_limb_t n_factor_one_line(mp_limb_t n, ulong iters)
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{
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mp_limb_t orig_n = n, in, square, sqrti, mod, factor, factoring = iters, iin;
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n *= FLINT_ONE_LINE_MULTIPLIER;
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iin = 0;
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in = n;
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while (factoring && (iin < in))
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{
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sqrti = n_sqrt(in);
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sqrti++;
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square = sqrti*sqrti;
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mod = square - in;
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if (n_is_square(mod))
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{
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factor = n_sqrt(mod);
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sqrti -= factor;
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factor = n_gcd_full(orig_n, sqrti);
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if (factor != UWORD(1))
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{
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return factor;
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}
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}
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factoring--;
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iin = in;
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in += n;
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}
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return 0;
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}
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