xref: /freebsd/lib/msun/man/acosh.3 (revision 3a8617a83f16ffc9db4f96e1f0f21af94078e6b1)
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32.\"     from: @(#)acosh.3	5.2 (Berkeley) 5/6/91
33.\"	$Id: acosh.3,v 1.4 1993/10/29 22:57:20 jtc Exp $
34.\"
35.Dd May 6, 1991
36.Dt ACOSH 3
37.Os BSD 4.3
38.Sh NAME
39.Nm acosh
40.Nd inverse hyperbolic cosine function
41.Sh SYNOPSIS
42.Fd #include <math.h>
43.Ft double
44.Fn acosh "double x"
45.Sh DESCRIPTION
46The
47.Fn acosh
48function computes the inverse hyperbolic cosine
49of the real
50argument
51.Ar x .
52For a discussion of error due to roundoff, see
53.Xr math 3 .
54.Sh RETURN VALUES
55The
56.Fn acosh
57function
58returns the inverse hyperbolic cosine of
59.Ar x .
60On the
61.Tn VAX
62and
63.Tn Tahoe ,
64if the argument is less than one
65.Fn acosh
66sets the global variable
67.Va errno
68to
69.Er EDOM
70and
71causes a reserved operand fault.
72.Sh SEE ALSO
73.Xr asinh 3 ,
74.Xr atanh 3 ,
75.Xr exp 3 ,
76.Xr infnan 3 ,
77.Xr math 3
78.Sh HISTORY
79The
80.Fn acosh
81function appeared in
82.Bx 4.3 .
83