1TANH(3P)                   POSIX Programmer's Manual                  TANH(3P)
2
3
4

PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10

NAME

12       tanh, tanhf, tanhl — hyperbolic tangent functions
13

SYNOPSIS

15       #include <math.h>
16
17       double tanh(double x);
18       float tanhf(float x);
19       long double tanhl(long double x);
20

DESCRIPTION

22       The functionality described on this reference page is aligned with  the
23       ISO C  standard.  Any  conflict between the requirements described here
24       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
25       defers to the ISO C standard.
26
27       These  functions shall compute the hyperbolic tangent of their argument
28       x.
29
30       An application wishing to check for error situations should  set  errno
31       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
32       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
33       FE_DIVBYZERO  |  FE_OVERFLOW  | FE_UNDERFLOW) is non-zero, an error has
34       occurred.
35

RETURN VALUE

37       Upon successful completion, these functions shall return the hyperbolic
38       tangent of x.
39
40       If x is NaN, a NaN shall be returned.
41
42       If x is ±0, x shall be returned.
43
44       If x is ±Inf, ±1 shall be returned.
45
46       If x is subnormal, a range error may occur
47       and x should be returned.
48
49       If  x  is  not  returned,  tanh(), tanhf(), and tanhl() shall return an
50       implementation-defined value no  greater  in  magnitude  than  DBL_MIN,
51       FLT_MIN, and LDBL_MIN, respectively.
52

ERRORS

54       These functions may fail if:
55
56       Range Error The value of x is subnormal.
57
58                   If  the  integer expression (math_errhandling & MATH_ERRNO)
59                   is non-zero, then errno shall be set to [ERANGE].   If  the
60                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
61                   non-zero, then the underflow floating-point exception shall
62                   be raised.
63
64       The following sections are informative.
65

EXAMPLES

67       None.
68

APPLICATION USAGE

70       On   error,   the   expressions  (math_errhandling  &  MATH_ERRNO)  and
71       (math_errhandling & MATH_ERREXCEPT) are independent of each other,  but
72       at least one of them must be non-zero.
73

RATIONALE

75       None.
76

FUTURE DIRECTIONS

78       None.
79

SEE ALSO

81       atanh(), feclearexcept(), fetestexcept(), isnan(), tan()
82
83       The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
84       Error Conditions for Mathematical Functions, <math.h>
85

87       Portions of this text are reprinted and reproduced in  electronic  form
88       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
89       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
90       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
91       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
92       event of any discrepancy between this version and the original IEEE and
93       The Open Group Standard, the original IEEE and The Open Group  Standard
94       is  the  referee document. The original Standard can be obtained online
95       at http://www.opengroup.org/unix/online.html .
96
97       Any typographical or formatting errors that appear  in  this  page  are
98       most likely to have been introduced during the conversion of the source
99       files to man page format. To report such errors,  see  https://www.ker‐
100       nel.org/doc/man-pages/reporting_bugs.html .
101
102
103
104IEEE/The Open Group                  2017                             TANH(3P)
Impressum