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dfd2257a UD |
1 | /* Compute complex base 10 logarithm. |
2 | Copyright (C) 1997 Free Software Foundation, Inc. | |
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 | |
7 | modify it under the terms of the GNU Library General Public License as | |
8 | published by the Free Software Foundation; either version 2 of the | |
9 | License, or (at your option) any later version. | |
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 | |
14 | Library General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Library General Public | |
17 | License along with the GNU C Library; see the file COPYING.LIB. If not, | |
18 | write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include <complex.h> | |
22 | #include <math.h> | |
23 | ||
24 | #include "math_private.h" | |
25 | ||
26 | ||
27 | __complex__ double | |
28 | __clog10 (__complex__ double x) | |
29 | { | |
30 | __complex__ double result; | |
31 | int rcls = fpclassify (__real__ x); | |
32 | int icls = fpclassify (__imag__ x); | |
33 | ||
34 | if (rcls == FP_ZERO && icls == FP_ZERO) | |
35 | { | |
36 | /* Real and imaginary part are 0.0. */ | |
37 | __imag__ result = signbit (__real__ x) ? M_PI : 0.0; | |
38 | __imag__ result = __copysign (__imag__ result, __imag__ x); | |
39 | /* Yes, the following line raises an exception. */ | |
40 | __real__ result = -1.0 / fabs (__real__ x); | |
41 | } | |
42 | else if (rcls != FP_NAN && icls != FP_NAN) | |
43 | { | |
44 | /* Neither real nor imaginary part is NaN. */ | |
45 | __real__ result = __ieee754_log10 (__ieee754_hypot (__real__ x, | |
46 | __imag__ x)); | |
bd355af0 | 47 | __imag__ result = M_LOG10E * __ieee754_atan2 (__imag__ x, __real__ x); |
dfd2257a UD |
48 | } |
49 | else | |
50 | { | |
51 | __imag__ result = __nan (""); | |
52 | if (rcls == FP_INFINITE || icls == FP_INFINITE) | |
53 | /* Real or imaginary part is infinite. */ | |
54 | __real__ result = HUGE_VAL; | |
55 | else | |
56 | __real__ result = __nan (""); | |
57 | } | |
58 | ||
59 | return result; | |
60 | } | |
61 | weak_alias (__clog10, clog10) | |
62 | #ifdef NO_LONG_DOUBLE | |
63 | strong_alias (__clog10, __clog10l) | |
64 | weak_alias (__clog10, clog10l) | |
65 | #endif |