1 /* Compute complex base 10 logarithm.
2 Copyright (C) 1997-2012 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
6 The GNU C Library is free software; you can redistribute it and/or
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.
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 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
22 #include <math_private.h>
26 #define M_LOG10_2f 0.3010299956639811952137388947244930267682f
29 __clog10f (__complex__ float x)
31 __complex__ float result;
32 int rcls = fpclassify (__real__ x);
33 int icls = fpclassify (__imag__ x);
35 if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0))
37 /* Real and imaginary part are 0.0. */
38 __imag__ result = signbit (__real__ x) ? M_PI : 0.0;
39 __imag__ result = __copysignf (__imag__ result, __imag__ x);
40 /* Yes, the following line raises an exception. */
41 __real__ result = -1.0 / fabsf (__real__ x);
43 else if (__builtin_expect (rcls != FP_NAN && icls != FP_NAN, 1))
45 /* Neither real nor imaginary part is NaN. */
46 float absx = fabsf (__real__ x), absy = fabsf (__imag__ x);
50 if (absx > FLT_MAX / 2.0f)
53 absx = __scalbnf (absx, scale);
54 absy = (absy >= FLT_MIN * 2.0f ? __scalbnf (absy, scale) : 0.0f);
56 else if (absy > FLT_MAX / 2.0f)
59 absx = (absx >= FLT_MIN * 2.0f ? __scalbnf (absx, scale) : 0.0f);
60 absy = __scalbnf (absy, scale);
62 else if (absx < FLT_MIN && absy < FLT_MIN)
65 absx = __scalbnf (absx, scale);
66 absy = __scalbnf (absy, scale);
69 d = __ieee754_hypotf (absx, absy);
71 __real__ result = __ieee754_log10f (d) - scale * M_LOG10_2f;
72 __imag__ result = M_LOG10E * __ieee754_atan2f (__imag__ x, __real__ x);
76 __imag__ result = __nanf ("");
77 if (rcls == FP_INFINITE || icls == FP_INFINITE)
78 /* Real or imaginary part is infinite. */
79 __real__ result = HUGE_VALF;
81 __real__ result = __nanf ("");
87 weak_alias (__clog10f, clog10f)