| /** |
| * This file has no copyright assigned and is placed in the Public Domain. |
| * This file is part of the w64 mingw-runtime package. |
| * No warranty is given; refer to the file DISCLAIMER.PD within this package. |
| */ |
| /* |
| Contributed by Danny Smith |
| 2005-01-04 |
| |
| FIXME: This needs some serious numerical analysis. |
| */ |
| |
| #include <math.h> |
| #include <complex.h> |
| #include <errno.h> |
| |
| /* catan (z) = -I/2 * clog ((I + z) / (I - z)) */ |
| |
| #ifndef _M_PI_2L |
| #define _M_PI_2L 1.5707963267948966192313L |
| #endif |
| |
| long double complex |
| catanl (long double complex Z) |
| { |
| long double complex Res; |
| long double complex Tmp; |
| long double x = __real__ Z; |
| long double y = __imag__ Z; |
| |
| if ( x == 0.0L && (1.0L - fabsl (y)) == 0.0L) |
| { |
| errno = ERANGE; |
| __real__ Res = HUGE_VALL; |
| __imag__ Res = HUGE_VALL; |
| } |
| else if (isinf (hypotl (x, y))) |
| { |
| __real__ Res = (x > 0 ? _M_PI_2L : -_M_PI_2L); |
| __imag__ Res = 0.0L; |
| } |
| else |
| { |
| __real__ Tmp = - x; |
| __imag__ Tmp = 1.0L - y; |
| |
| __real__ Res = x; |
| __imag__ Res = y + 1.0L; |
| |
| Tmp = clogl (Res/Tmp); |
| __real__ Res = - 0.5L * __imag__ Tmp; |
| __imag__ Res = 0.5L * __real__ Tmp; |
| } |
| |
| return Res; |
| } |