1 /*
2 Copyright (C) 2012 Fredrik Johansson
3
4 This file is part of Arb.
5
6 Arb is free software: you can redistribute it and/or modify it under
7 the terms of the GNU Lesser General Public License (LGPL) as published
8 by the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version. See <http://www.gnu.org/licenses/>.
10 */
11
12 #include "arb.h"
13
14 int
arb_overlaps(const arb_t x,const arb_t y)15 arb_overlaps(const arb_t x, const arb_t y)
16 {
17 arf_t t;
18 arf_struct u[4];
19 int result;
20
21 if (mag_is_inf(arb_radref(x)) || mag_is_inf(arb_radref(y)))
22 return 1;
23
24 if (arf_equal(arb_midref(x), arb_midref(y)))
25 return 1;
26
27 arf_init(t);
28
29 /* |xm - ym| <= xr + yr */
30
31 if (arf_cmp(arb_midref(x), arb_midref(y)) >= 0)
32 {
33 arf_init_set_shallow(u + 0, arb_midref(x));
34 arf_init_neg_shallow(u + 1, arb_midref(y));
35 }
36 else
37 {
38 arf_init_neg_shallow(u + 0, arb_midref(x));
39 arf_init_set_shallow(u + 1, arb_midref(y));
40 }
41
42 arf_init_neg_mag_shallow(u + 2, arb_radref(x));
43 arf_init_neg_mag_shallow(u + 3, arb_radref(y));
44
45 arf_sum(t, u, 4, MAG_BITS, ARF_RND_DOWN);
46 result = arf_sgn(t) <= 0;
47
48 arf_clear(t);
49
50 return result;
51 }
52
53