about summary refs log tree commit diff
path: root/math/s_clog10f.c
blob: 5a0c370de5423f49571ef546b2e927b1f3b54fa6 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
/* Compute complex base 10 logarithm.
   Copyright (C) 1997-2012 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <complex.h>
#include <math.h>
#include <math_private.h>
#include <float.h>

/* log_10 (2).  */
#define M_LOG10_2f 0.3010299956639811952137388947244930267682f

__complex__ float
__clog10f (__complex__ float x)
{
  __complex__ float result;
  int rcls = fpclassify (__real__ x);
  int icls = fpclassify (__imag__ x);

  if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0))
    {
      /* Real and imaginary part are 0.0.  */
      __imag__ result = signbit (__real__ x) ? M_PI : 0.0;
      __imag__ result = __copysignf (__imag__ result, __imag__ x);
      /* Yes, the following line raises an exception.  */
      __real__ result = -1.0 / fabsf (__real__ x);
    }
  else if (__builtin_expect (rcls != FP_NAN && icls != FP_NAN, 1))
    {
      /* Neither real nor imaginary part is NaN.  */
      float absx = fabsf (__real__ x), absy = fabsf (__imag__ x);
      float d;
      int scale = 0;

      if (absx > FLT_MAX / 2.0f)
	{
	  scale = -1;
	  absx = __scalbnf (absx, scale);
	  absy = (absy >= FLT_MIN * 2.0f ? __scalbnf (absy, scale) : 0.0f);
	}
      else if (absy > FLT_MAX / 2.0f)
	{
	  scale = -1;
	  absx = (absx >= FLT_MIN * 2.0f ? __scalbnf (absx, scale) : 0.0f);
	  absy = __scalbnf (absy, scale);
	}
      else if (absx < FLT_MIN && absy < FLT_MIN)
	{
	  scale = FLT_MANT_DIG;
	  absx = __scalbnf (absx, scale);
	  absy = __scalbnf (absy, scale);
	}

      d = __ieee754_hypotf (absx, absy);

      __real__ result = __ieee754_log10f (d) - scale * M_LOG10_2f;
      __imag__ result = M_LOG10E * __ieee754_atan2f (__imag__ x, __real__ x);
    }
  else
    {
      __imag__ result = __nanf ("");
      if (rcls == FP_INFINITE || icls == FP_INFINITE)
	/* Real or imaginary part is infinite.  */
	__real__ result = HUGE_VALF;
      else
	__real__ result = __nanf ("");
    }

  return result;
}
#ifndef __clog10f
weak_alias (__clog10f, clog10f)
#endif