pqc/external/flint-2.4.3/fmpq/next_minimal.c
2014-05-24 23:16:06 +02:00

100 lines
2.5 KiB
C

/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2011 Fredrik Johansson
******************************************************************************/
#include "fmpq.h"
void
_fmpq_next_minimal(fmpz_t rnum, fmpz_t rden,
const fmpz_t num, const fmpz_t den)
{
fmpz p, q;
p = *num;
q = *den;
if (!COEFF_IS_MPZ(p) && !COEFF_IS_MPZ(q))
{
if (p < q && p)
{
*rnum = q;
*rden = p;
return;
}
while (q < p)
{
q++;
if (n_gcd(p, q) == 1)
{
*rnum = q;
*rden = p;
return;
}
}
*rnum = 1;
fmpz_set_ui(rden, p + 1);
}
else
{
fmpz_t t;
if (fmpz_cmp(num, den) < 0)
{
fmpz_set(rnum, num);
fmpz_set(rden, den);
fmpz_swap(rnum, rden);
return;
}
fmpz_init(t);
fmpz_set(rnum, num);
fmpz_set(rden, den);
while (fmpz_cmp(rden, rnum) < 0)
{
fmpz_add_ui(rden, rden, UWORD(1));
fmpz_gcd(t, rden, rnum);
if (fmpz_is_one(t))
{
fmpz_swap(rnum, rden);
fmpz_clear(t);
return;
}
}
fmpz_add_ui(rden, rden, UWORD(1));
fmpz_one(rnum);
fmpz_clear(t);
}
}
void
fmpq_next_minimal(fmpq_t res, const fmpq_t x)
{
_fmpq_next_minimal(fmpq_numref(res), fmpq_denref(res),
fmpq_numref(x), fmpq_denref(x));
}