2 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
3 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
4 .\" <mtk.manpages@gmail.com>
6 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
8 .\" References consulted:
9 .\" Linux libc source code
10 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
12 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
13 .\" Modified 2002-07-27 by Walter Harms
14 .\" (walter.harms@informatik.uni-oldenburg.de)
16 .TH tanh 3 (date) "Linux man-pages (unreleased)"
18 tanh, tanhf, tanhl \- hyperbolic tangent function
21 .RI ( libm ", " \-lm )
26 .BI "double tanh(double " x );
27 .BI "float tanhf(float " x );
28 .BI "long double tanhl(long double " x );
32 Feature Test Macro Requirements for glibc (see
33 .BR feature_test_macros (7)):
39 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
40 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
41 || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
44 These functions return the hyperbolic tangent of
47 is defined mathematically as:
50 tanh(x) = sinh(x) / cosh(x)
53 On success, these functions return the hyperbolic tangent of
58 is a NaN, a NaN is returned.
62 is +0 (\-0), +0 (\-0) is returned.
66 is positive infinity (negative infinity),
69 .\" POSIX.1-2001 documents an optional range error (underflow)
71 .\" glibc 2.8 does not do this.
75 For an explanation of the terms used in this section, see
81 Interface Attribute Value
88 T} Thread safety MT-Safe