libm: Sync with FreeBSD (~50 math functions added)
[dragonfly.git] / lib / libm / man / tanh.3
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1.\" Copyright (c) 1991 The Regents of the University of California.
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28.\" from: @(#)tanh.3 5.1 (Berkeley) 5/2/91
74dfd0cf 29.\" $NetBSD: tanh.3,v 1.15 2011/11/17 23:46:32 wiz Exp $
b638a263 30.\"
74dfd0cf 31.Dd September 18, 2011
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32.Dt TANH 3
33.Os
34.Sh NAME
35.Nm tanh ,
36.Nm tanhf
37.Nd hyperbolic tangent function
38.Sh LIBRARY
39.Lb libm
40.Sh SYNOPSIS
41.In math.h
42.Ft double
43.Fn tanh "double x"
44.Ft float
45.Fn tanhf "float x"
46.Sh DESCRIPTION
47The
48.Fn tanh
49and
50.Fn tanhf
51functions compute the hyperbolic tangent of
52.Fa x .
53For a discussion of error due to roundoff, see
54.Xr math 3 .
55.Sh RETURN VALUES
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56Upon successful completion,
57these functions return the hyperbolic tangent value.
58The following may also occur:
59.Bl -enum -offset indent
60.It
61If
62.Fa x
63is \*(Pm 0,
64.Fa x
65is returned.
66.It
67If
68.Fa x
69is \*(Na, a \*(Na is returned.
70.It
71If
72.Fa x
73is positive infinity, a value 1 is returned;
74if
75.Fa x
76is negative infinity, -1 is returned.
77.It
78If
79.Fa x
80is subnormal, a range error can occur and
81.Fa x
82is returned.
83.El
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84.Sh SEE ALSO
85.Xr acos 3 ,
86.Xr asin 3 ,
87.Xr atan 3 ,
88.Xr atan2 3 ,
89.Xr cos 3 ,
90.Xr cosh 3 ,
91.Xr math 3 ,
92.Xr sin 3 ,
93.Xr sinh 3 ,
94.Xr tan 3
95.Sh STANDARDS
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96The described functions conform to
97.St -isoC-99 .