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glibc  2.9
Functions
s_catan.c File Reference
#include <complex.h>
#include <math.h>
#include "math_private.h"
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Functions

__complex__ double __catan (__complex__ double x)

Function Documentation

__complex__ double __catan ( __complex__ double  x)

Definition at line 28 of file s_catan.c.

{
  __complex__ double res;
  int rcls = fpclassify (__real__ x);
  int icls = fpclassify (__imag__ x);

  if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
    {
      if (rcls == FP_INFINITE)
       {
         __real__ res = __copysign (M_PI_2, __real__ x);
         __imag__ res = __copysign (0.0, __imag__ x);
       }
      else if (icls == FP_INFINITE)
       {
         if (rcls >= FP_ZERO)
           __real__ res = __copysign (M_PI_2, __real__ x);
         else
           __real__ res = __nan ("");
         __imag__ res = __copysign (0.0, __imag__ x);
       }
      else if (icls == FP_ZERO || icls == FP_INFINITE)
       {
         __real__ res = __nan ("");
         __imag__ res = __copysign (0.0, __imag__ x);
       }
      else
       {
         __real__ res = __nan ("");
         __imag__ res = __nan ("");
       }
    }
  else if (rcls == FP_ZERO && icls == FP_ZERO)
    {
      res = x;
    }
  else
    {
      double r2, num, den;

      r2 = __real__ x * __real__ x;

      den = 1 - r2 - __imag__ x * __imag__ x;

      __real__ res = 0.5 * __ieee754_atan2 (2.0 * __real__ x, den);

      num = __imag__ x + 1.0;
      num = r2 + num * num;

      den = __imag__ x - 1.0;
      den = r2 + den * den;

      __imag__ res = 0.25 * __ieee754_log (num / den);
    }

  return res;
}

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