.TH ASINH 3M "4 August 1985"
.UC 4
.ds up \fIulp\fR
.SH NAME
asinh, acosh, atanh \- inverse hyperbolic functions
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.B double asinh(x)
.B double x;
.PP
.B double acosh(x)
.B double x;
.PP
.B double atanh(x)
.B double x;
.fi
.SH DESCRIPTION
These functions compute the designated inverse hyperbolic functions for real
arguments.
.SH SEE ALSO
intro(3M), exp(3M), infnan(3M)
.SH ERROR (due to Roundoff etc.)
These functions inherit much of their error from log1p described in
exp(3M).  On a VAX, acosh is accurate to about 3 \*(ups,
asinh and atanh to about 2 \*(ups.
An \*(up is one \fIU\fRnit in the \fIL\fRast \fIP\fRlace carried.
.SH DIAGNOSTICS
Acosh returns the reserved operand on a VAX if the argument is less than 1.
.PP
Atanh returns the reserved operand on a VAX if the argument has absolute
value bigger than or equal to 1.
.SH AUTHOR
W. Kahan, Kwok\-Choi Ng