SYNOPSIS
       #include <complex.h>

       double complex cacosh(double complex z);
       float complex cacoshf(float complex z);
       long double complex cacoshl(long double complex z);

       Link with -lm.

DESCRIPTION
       The  cacosh()  function calculates the complex arc hyperpolic cosine of
       z.  If y = cacosh(z), then z = ccosh(y).  The imaginary part  of  y  is
       chosen in the interval [-pi,pi].  The real part of y is chosen non-neg-
       ative.

       One has:

           cacosh(z) = (0.5) * clog((1 + z) / (1 - z))

VERSIONS
       These functions first appeared in glibc in version 2.1.

CONFORMING TO
       C99.

SEE ALSO
       acosh(3), cabs(3), cimag(3), complex(7)

COLOPHON
       This page is part of release 3.23 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.