55 lines
1.7 KiB
C
55 lines
1.7 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) 2011 Fredrik Johansson
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******************************************************************************/
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#include "arith.h"
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/* Small enough that a numerical computation is safe */
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#define DOUBLE_CUTOFF (UWORD(1) << 21)
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void
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arith_dedekind_sum_coprime(fmpq_t s, const fmpz_t h, const fmpz_t k)
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{
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if (fmpz_cmp_ui(k, DOUBLE_CUTOFF) < 0)
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{
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double t;
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t = arith_dedekind_sum_coprime_d(*h, *k) * (6 * (*k));
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/* Round to nearest after truncation */
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if (t > 0)
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t += 0.5;
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else
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t -= 0.5;
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fmpz_set_d(fmpq_numref(s), t);
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fmpz_set_ui(fmpq_denref(s), UWORD(6) * (*k));
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fmpq_canonicalise(s);
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}
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else
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{
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arith_dedekind_sum_coprime_large(s, h, k);
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}
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}
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