xref: /freebsd/lib/msun/man/atanh.3 (revision 64890443c1b144b289df30a5123d179955bc8c92)

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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 LIBRARY
.Lb libm
.Sh SYNOPSIS
.In 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 .