.\" Copyright 2002 Walter Harms(walter.harms@informatik.uni-oldenburg.de)

.\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gmail.com>

.\"

.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)

.\" Distributed under GPL

.\" %%%LICENSE_END

.\"

.TH CACOSH 3 2015-04-19 "" "Linux Programmer's Manual"

.SH NAME

cacosh, cacoshf, cacoshl \- complex arc hyperbolic cosine

.SH SYNOPSIS

.B #include <complex.h>

.PP

.BI "double complex cacosh(double complex " z );

.br

.BI "float complex cacoshf(float complex " z );

.br

.BI "long double complex cacoshl(long double complex " z );

.PP

Link with \fI\-lm\fP.

.SH DESCRIPTION

These functions calculate the complex arc hyperbolic cosine of

.IR z .

If \fIy\ =\ cacosh(z)\fP, then \fIz\ =\ ccosh(y)\fP.

The imaginary part of

.I y

is chosen in the interval [\-pi,pi].

The real part of

.I y

is chosen nonnegative.

.PP

One has:

.PP

.nf

    cacosh(z) = 2 * clog(csqrt((z + 1) / 2) + csqrt((z \- 1) / 2))

.fi

.SH VERSIONS

These functions first appeared in glibc in version 2.1.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lbw30 lb lb

l l l.

Interface	Attribute	Value

T{

.BR cacosh (),

.BR cacoshf (),

.BR cacoshl ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

.SH EXAMPLE

.EX

/* Link with "\-lm" */

#include <complex.h>

#include <stdlib.h>

#include <unistd.h>

#include <stdio.h>

int

main(int argc, char *argv[])

{

    double complex z, c, f;

    if (argc != 3) {

        fprintf(stderr, "Usage: %s <real> <imag>\\n", argv[0]);

        exit(EXIT_FAILURE);

    }

    z = atof(argv[1]) + atof(argv[2]) * I;

    c = cacosh(z);

    printf("cacosh() = %6.3f %6.3f*i\\n", creal(c), cimag(c));

    f = 2 * clog(csqrt((z + 1)/2) + csqrt((z \- 1)/2));

    printf("formula  = %6.3f %6.3f*i\\n", creal(f2), cimag(f2));

    exit(EXIT_SUCCESS);

}

.EE

.SH SEE ALSO

.BR acosh (3),

.BR cabs (3),

.BR ccosh (3),

.BR cimag (3),

.BR complex (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.