math/s_clogf.c

   1 /* Compute complex natural 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.
   5
   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.
  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    Lesser General Public License for more details.
  15
  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/>.  */
  19
  20 #include <complex.h>
  21 #include <math.h>
  22 #include <math_private.h>
  23 #include <float.h>
  24
  25 __complex__ float
  26 __clogf (__complex__ float x)
  27 {
  28   __complex__ float result;
  29   int rcls = fpclassify (__real__ x);
  30   int icls = fpclassify (__imag__ x);
  31
  32   if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0))
  33     {
  34       /* Real and imaginary part are 0.0.  */
  35       __imag__ result = signbit (__real__ x) ? M_PI : 0.0;
  36       __imag__ result = __copysignf (__imag__ result, __imag__ x);
  37       /* Yes, the following line raises an exception.  */
  38       __real__ result = -1.0 / fabsf (__real__ x);
  39     }
  40   else if (__builtin_expect (rcls != FP_NAN && icls != FP_NAN, 1))
  41     {
  42       /* Neither real nor imaginary part is NaN.  */
  43       float d;
  44       int scale = 0;
  45
  46       if (fabsf (__real__ x) > FLT_MAX / 2.0f
  47           || fabsf (__imag__ x) > FLT_MAX / 2.0f)
  48         {
  49           scale = -1;
  50           __real__ x = __scalbnf (__real__ x, scale);
  51           __imag__ x = __scalbnf (__imag__ x, scale);
  52         }
  53       else if (fabsf (__real__ x) < FLT_MIN
  54                && fabsf (__imag__ x) < FLT_MIN)
  55         {
  56           scale = FLT_MANT_DIG;
  57           __real__ x = __scalbnf (__real__ x, scale);
  58           __imag__ x = __scalbnf (__imag__ x, scale);
  59         }
  60
  61       d = __ieee754_hypotf (__real__ x, __imag__ x);
  62
  63       __real__ result = __ieee754_logf (d) - scale * (float) M_LN2;
  64       __imag__ result = __ieee754_atan2f (__imag__ x, __real__ x);
  65     }
  66   else
  67     {
  68       __imag__ result = __nanf ("");
  69       if (rcls == FP_INFINITE || icls == FP_INFINITE)
  70         /* Real or imaginary part is infinite.  */
  71         __real__ result = HUGE_VALF;
  72       else
  73         __real__ result = __nanf ("");
  74     }
  75
  76   return result;
  77 }
  78 #ifndef __clogf
  79 weak_alias (__clogf, clogf)
  80 #endif