arb/fmpr/cmp.c
2016-04-26 17:20:05 +02:00

53 lines
1.3 KiB
C

/*
Copyright (C) 2012 Fredrik Johansson
This file is part of Arb.
Arb 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 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "fmpr.h"
int
fmpr_cmp(const fmpr_t x, const fmpr_t y)
{
int res, xsign, ysign;
fmpr_t t;
if (fmpr_equal(x, y))
return 0;
if (fmpr_is_special(x) || fmpr_is_special(y))
{
if (fmpr_is_nan(x) || fmpr_is_nan(y))
return 0;
if (fmpr_is_zero(y)) return fmpr_sgn(x);
if (fmpr_is_zero(x)) return -fmpr_sgn(y);
if (fmpr_is_pos_inf(x)) return 1;
if (fmpr_is_neg_inf(y)) return 1;
return -1;
}
xsign = fmpr_sgn(x);
ysign = fmpr_sgn(y);
if (xsign != ysign)
return (xsign < 0) ? -1 : 1;
/* Reduces to integer comparison if bottom exponents are the same */
if (fmpz_equal(fmpr_expref(x), fmpr_expref(y)))
return fmpz_cmp(fmpr_manref(x), fmpr_manref(y)) < 0 ? -1 : 1;
/* TODO: compare position of top exponents to avoid subtraction */
fmpr_init(t);
fmpr_sub(t, x, y, 2, FMPR_RND_DOWN);
res = fmpr_sgn(t);
fmpr_clear(t);
return res;
}