cacos man page


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

cacos, cacosf, cacosl — complex arc cosine functions


#include <complex.h>

double complex cacos(double complex z);
float complex cacosf(float complex z);
long double complex cacosl(long double complex z);


The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2008 defers to the ISO C standard.

These functions shall compute the complex arc cosine of z, with branch cuts outside the interval [-1, +1] along the real axis.

Return Value

These functions shall return the complex arc cosine value, in the range of a strip mathematically unbounded along the imaginary axis and in the interval [0, π] along the real axis.


No errors are defined.

The following sections are informative.

See Also


The Base Definitions volume of POSIX.1‐2008, <complex.h>


2013 IEEE/The Open Group POSIX Programmer's Manual