69 lines
1.9 KiB
C
69 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) 2011 Fredrik Johansson
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******************************************************************************/
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#include "fmpq.h"
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void
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_fmpq_next_calkin_wilf(fmpz_t rnum, fmpz_t rden,
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const fmpz_t num, const fmpz_t den)
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{
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fmpz n, d;
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n = *num;
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d = *den;
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if (!COEFF_IS_MPZ(n) && !COEFF_IS_MPZ(d))
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{
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/* This does not overflow, as the larger part at most doubles */
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fmpz_set_ui(rnum, d);
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fmpz_set_ui(rden, d*(n / d) + d - (n % d));
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}
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else
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{
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fmpz_t q, r, t;
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fmpz_init(q);
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fmpz_init(r);
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fmpz_init(t);
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fmpz_fdiv_qr(q, r, num, den);
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fmpz_set(rnum, den);
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fmpz_mul(t, q, den);
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fmpz_add(rden, t, den);
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fmpz_sub(rden, rden, r);
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fmpz_clear(q);
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fmpz_clear(r);
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fmpz_clear(t);
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}
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}
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void
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fmpq_next_calkin_wilf(fmpq_t res, const fmpq_t x)
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{
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_fmpq_next_calkin_wilf(fmpq_numref(res), fmpq_denref(res),
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fmpq_numref(x), fmpq_denref(x));
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}
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