| /** |
| * 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. |
| */ |
| /* |
| casin.c |
| Contributed by Danny Smith |
| 2003-10-20 |
| */ |
| |
| #include <math.h> |
| #include <complex.h> |
| |
| /* casin (Z ) = -I * clog(I * Z + csqrt (1.0 - Z * Z))) */ |
| |
| double complex casin (double complex Z) |
| { |
| double complex Res; |
| double x, y; |
| |
| x = __real__ Z; |
| y = __imag__ Z; |
| |
| if (y == 0.0) |
| { |
| __real__ Res = asin (x); |
| __imag__ Res = 0.0; |
| } |
| else /* -I * clog(I * Z + csqrt(1.0 - Z * Z))) */ |
| { |
| double complex ZZ; |
| |
| /* Z * Z = ((x - y) * (x + y)) + (2.0 * x * y) * I */ |
| /* calculate 1 - Z * Z */ |
| __real__ ZZ = 1.0 - (x - y) * (x + y); |
| __imag__ ZZ = -2.0 * x * y; |
| ZZ = csqrt (ZZ); |
| |
| |
| /* add I * Z to ZZ */ |
| |
| __real__ ZZ -= y; |
| __imag__ ZZ += x; |
| |
| ZZ = clog (ZZ); |
| |
| /* mult by -I */ |
| __real__ Res = __imag__ ZZ; |
| __imag__ Res = - __real__ ZZ; |
| } |
| return (Res); |
| } |