Compute the complex arc cosine
#include <complex.h> double complex cacos( double complex z ); float complex cacosf( float complex z ); long double complex cacosl( long double complex z );
These functions compute the complex arc cosine of z, with branch cuts outside the interval [−1, +1] along the real axis.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
The complex arc cosine of z, in the range [0; Inf) along the real axis and in the range [−iπ; iπ] along the imaginary axis.
| If z is: | These functions return: | Errors: |
|---|---|---|
| ±0 + 0i | π/2 - 0i | — |
| ±0 - 0i | π/2 + 0i | — |
| ±0 + NaNi | π/2 + NaNi | — |
| x + Infi, for any finite x | π/2 - Infi | — |
| x + NaNi, for any nonzero finite x | NaN + NaNi | — |
| -Inf + yi, for any positive finite y | π - Infi | — |
| -Inf - yi, for any positive finite y | π + Infi | — |
| Inf + yi, for any positive finite y | 0 - Infi | — |
| Inf - yi, for any negative finite y | 0 + Infi | — |
| -Inf + Infi | 3π/4 - Infi | — |
| Inf + Infi | π/4 - Infi | — |
| ±Inf + NaNi | NaN ± Infi, where the sign of the imaginary part is unspecified | — |
| NaN + yi, for any finite y | NaN + NaNi | — |
| NaN + Infi | NaN - Infi | — |
| NaN - Infi | NaN + Infi | — |
| NaN ± NaNi | NaN + NaNi | — |
These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | No |
| Signal handler | No |
| Thread | Yes |