xref: /freebsd/lib/msun/man/atanh.3 (revision a307d598387eeb7d775332066d996ab0dadf7e5f)

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.\"     from: @(#)atanh.3	5.2 (Berkeley) 5/6/91
.\" $FreeBSD$
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.Dd May 6, 1991
.Dt ATANH 3
.Os
.Sh NAME
.Nm atanh ,
.Nm atanhf
.Nd inverse hyperbolic tangent functions
.Sh SYNOPSIS
.Fd #include <math.h>
.Ft double
.Fn atanh "double x"
.Ft float
.Fn atanhf "float x"
.Sh DESCRIPTION
The
.Fn  atanh
and the
.Fn  atanhf
functions compute the inverse hyperbolic tangent
of the real
argument
.Ar x .
For a discussion of error due to roundoff, see
.Xr math 3 .
.Sh RETURN VALUES
The
.Fn atanh
and the
.Fn atanhf
functions
return the inverse hyperbolic tangent of
.Ar x
if successful.
On the
.Tn VAX
and
.Tn Tahoe ,
if the argument has absolute value
bigger than or equal to 1,
.Fn atanh
sets the global variable
.Va errno
to
.Er EDOM
and
a reserved operand fault is generated.
.Sh SEE ALSO
.Xr acosh 3 ,
.Xr asinh 3 ,
.Xr exp 3 ,
.Xr math 3
.Sh HISTORY
The
.Fn atanh
function appeared in
.Bx 4.3 .