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/*
Copyright (C) 2011 Fredrik Johansson
This file is part of FLINT.
FLINT 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 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpq.h"
void
_fmpq_next_calkin_wilf(fmpz_t rnum, fmpz_t rden,
const fmpz_t num, const fmpz_t den)
{
fmpz n, d;
n = *num;
d = *den;
if (!COEFF_IS_MPZ(n) && !COEFF_IS_MPZ(d))
{
/* This does not overflow, as the larger part at most doubles */
fmpz_set_ui(rnum, d);
fmpz_set_ui(rden, d*(n / d) + d - (n % d));
}
else
{
fmpz_t q, r, t;
fmpz_init(q);
fmpz_init(r);
fmpz_init(t);
fmpz_fdiv_qr(q, r, num, den);
fmpz_set(rnum, den);
fmpz_mul(t, q, den);
fmpz_add(rden, t, den);
fmpz_sub(rden, rden, r);
fmpz_clear(q);
fmpz_clear(r);
fmpz_clear(t);
}
}
void
fmpq_next_calkin_wilf(fmpq_t res, const fmpq_t x)
{
_fmpq_next_calkin_wilf(fmpq_numref(res), fmpq_denref(res),
fmpq_numref(x), fmpq_denref(x));
}