1 | /* Copyright (C) 2005-2022 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <stdbool.h> |
19 | #include <math.h> |
20 | #include <complex.h> |
21 | |
22 | attribute_hidden |
23 | long double _Complex |
24 | __multc3 (long double a, long double b, long double c, long double d) |
25 | { |
26 | long double ac, bd, ad, bc, x, y; |
27 | |
28 | ac = a * c; |
29 | bd = b * d; |
30 | ad = a * d; |
31 | bc = b * c; |
32 | |
33 | x = ac - bd; |
34 | y = ad + bc; |
35 | |
36 | if (isnan (x) && isnan (y)) |
37 | { |
38 | /* Recover infinities that computed as NaN + iNaN. */ |
39 | bool recalc = 0; |
40 | if (isinf (a) || isinf (b)) |
41 | { |
42 | /* z is infinite. "Box" the infinity and change NaNs in |
43 | the other factor to 0. */ |
44 | a = copysignl (isinf (a) ? 1 : 0, a); |
45 | b = copysignl (isinf (b) ? 1 : 0, b); |
46 | if (isnan (c)) c = copysignl (0, c); |
47 | if (isnan (d)) d = copysignl (0, d); |
48 | recalc = 1; |
49 | } |
50 | if (isinf (c) || isinf (d)) |
51 | { |
52 | /* w is infinite. "Box" the infinity and change NaNs in |
53 | the other factor to 0. */ |
54 | c = copysignl (isinf (c) ? 1 : 0, c); |
55 | d = copysignl (isinf (d) ? 1 : 0, d); |
56 | if (isnan (a)) a = copysignl (0, a); |
57 | if (isnan (b)) b = copysignl (0, b); |
58 | recalc = 1; |
59 | } |
60 | if (!recalc |
61 | && (isinf (ac) || isinf (bd) |
62 | || isinf (ad) || isinf (bc))) |
63 | { |
64 | /* Recover infinities from overflow by changing NaNs to 0. */ |
65 | if (isnan (a)) a = copysignl (0, a); |
66 | if (isnan (b)) b = copysignl (0, b); |
67 | if (isnan (c)) c = copysignl (0, c); |
68 | if (isnan (d)) d = copysignl (0, d); |
69 | recalc = 1; |
70 | } |
71 | if (recalc) |
72 | { |
73 | x = INFINITY * (a * c - b * d); |
74 | y = INFINITY * (a * d + b * c); |
75 | } |
76 | } |
77 | |
78 | return x + I * y; |
79 | } |
80 | |