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7799b7b3 | 1 | /* Compute projection of complex double value to Riemann sphere. |
4d3a563f | 2 | Copyright (C) 1997, 1999 Free Software Foundation, Inc. |
7799b7b3 UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
7799b7b3 UD |
10 | |
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 14 | Lesser General Public License for more details. |
7799b7b3 | 15 | |
41bdb6e2 AJ |
16 | You should have received a copy of the GNU Lesser General Public |
17 | License along with the GNU C Library; if not, write to the Free | |
18 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
19 | 02111-1307 USA. */ | |
7799b7b3 UD |
20 | |
21 | #include <complex.h> | |
22 | #include <math.h> | |
23 | ||
24 | ||
25 | __complex__ double | |
26 | __cproj (__complex__ double x) | |
27 | { | |
28 | __complex__ double res; | |
29 | ||
4d3a563f UD |
30 | if (isnan (__real__ x) && isnan (__imag__ x)) |
31 | return x; | |
32 | else if (!isfinite (__real__ x) || !isfinite (__imag__ x)) | |
7799b7b3 UD |
33 | { |
34 | __real__ res = INFINITY; | |
35 | __imag__ res = __copysign (0.0, __imag__ x); | |
36 | } | |
37 | else | |
38 | { | |
39 | double den = __real__ x * __real__ x + __imag__ x * __imag__ x + 1.0; | |
40 | ||
41 | __real__ res = (2.0 * __real__ x) / den; | |
42 | __imag__ res = (2.0 * __imag__ x) / den; | |
43 | } | |
44 | ||
45 | return res; | |
46 | } | |
47 | weak_alias (__cproj, cproj) | |
48 | #ifdef NO_LONG_DOUBLE | |
49 | strong_alias (__cproj, __cprojl) | |
50 | weak_alias (__cproj, cprojl) | |
51 | #endif |