.\"	$OpenBSD: catanh.3,v 1.2 2013/06/05 03:40:26 tedu Exp $
.\"
.\" Copyright (c) 2011 Martynas Venckus <martynas@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: June 5 2013 $
.Dt CATANH 3
.Os
.Sh NAME
.Nm catanh ,
.Nm catanhf ,
.Nm catanhl
.Nd complex inverse hyperbolic tangent
.Sh SYNOPSIS
.In complex.h
.Ft double complex
.Fn catanh "double complex z"
.Ft float complex
.Fn catanhf "float complex z"
.Ft long double complex
.Fn catanhl "long double complex z"
.Sh DESCRIPTION
The
.Fn catanh ,
.Fn catanhf
and
.Fn catanhl
functions compute the complex inverse hyperbolic tangent of
.Fa z .
.Pp
For all complex floating-point numbers
.Fa z ,
.Bd -literal -offset indent
catanh(z) = -i catan(iz).
.Ed
.Sh RETURN VALUES
The
.Fn catanh ,
.Fn catanhf
and
.Fn catanhl
functions return the complex inverse hyperbolic tangent of
.Fa z
with imaginary part in the interval
.Bq -Pi/2, Pi/2 ,
and unbounded real part.
.Sh SEE ALSO
.Xr cacosh 3 ,
.Xr casinh 3
.Sh STANDARDS
The
.Fn catanh ,
.Fn catanhf
and
.Fn catanhl
functions conform to
.St -isoC-99 .