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glibc  2.9
s_catanf.c
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00001 /* Return arc tangent of complex float value.
00002    Copyright (C) 1997 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <complex.h>
00022 #include <math.h>
00023 
00024 #include "math_private.h"
00025 
00026 
00027 __complex__ float
00028 __catanf (__complex__ float x)
00029 {
00030   __complex__ float res;
00031   int rcls = fpclassify (__real__ x);
00032   int icls = fpclassify (__imag__ x);
00033 
00034   if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
00035     {
00036       if (rcls == FP_INFINITE)
00037        {
00038          __real__ res = __copysignf (M_PI_2, __real__ x);
00039          __imag__ res = __copysignf (0.0, __imag__ x);
00040        }
00041       else if (icls == FP_INFINITE)
00042        {
00043          if (rcls >= FP_ZERO)
00044            __real__ res = __copysignf (M_PI_2, __real__ x);
00045          else
00046            __real__ res = __nanf ("");
00047          __imag__ res = __copysignf (0.0, __imag__ x);
00048        }
00049       else if (icls == FP_ZERO || icls == FP_INFINITE)
00050        {
00051          __real__ res = __nanf ("");
00052          __imag__ res = __copysignf (0.0, __imag__ x);
00053        }
00054       else
00055        {
00056          __real__ res = __nanf ("");
00057          __imag__ res = __nanf ("");
00058        }
00059     }
00060   else if (rcls == FP_ZERO && icls == FP_ZERO)
00061     {
00062       res = x;
00063     }
00064   else
00065     {
00066       float r2, num, den;
00067 
00068       r2 = __real__ x * __real__ x;
00069 
00070       den = 1 - r2 - __imag__ x * __imag__ x;
00071 
00072       __real__ res = 0.5 * __ieee754_atan2f (2.0 * __real__ x, den);
00073 
00074       num = __imag__ x + 1.0;
00075       num = r2 + num * num;
00076 
00077       den = __imag__ x - 1.0;
00078       den = r2 + den * den;
00079 
00080       __imag__ res = 0.25 * __ieee754_logf (num / den);
00081     }
00082 
00083   return res;
00084 }
00085 #ifndef __catanf
00086 weak_alias (__catanf, catanf)
00087 #endif