CACOS(3) Linux Programmer s Manual CACOS(3)

NAME cacos, cacosf, cacosl - complex arc cosine

SYNOPSIS #include <complex.h>

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

Link with -lm.

DESCRIPTION The cacos() function calculates the complex arc cosine of z. If y = cacos(z), then z = ccos(y). The real part of y is chosen in the interval [0,pi].

One has:

cacos(z) = -i clog(z + csqrt(z * z - 1))

VERSIONS These functions first appeared in glibc in version 2.1.


SEE ALSO ccos(3), clog(3), complex(7)

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

2008-08-11 CACOS(3)