1atanh(3)                   Library Functions Manual                   atanh(3)
2
3
4

NAME

6       atanh, atanhf, atanhl - inverse hyperbolic tangent function
7

LIBRARY

9       Math library (libm, -lm)
10

SYNOPSIS

12       #include <math.h>
13
14       double atanh(double x);
15       float atanhf(float x);
16       long double atanhl(long double x);
17
18   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
19
20       atanh():
21           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
22               || _XOPEN_SOURCE >= 500
23               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
24               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
25
26       atanhf(), atanhl():
27           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
28               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
29               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
30

DESCRIPTION

32       These  functions calculate the inverse hyperbolic tangent of x; that is
33       the value whose hyperbolic tangent is x.
34

RETURN VALUE

36       On success, these functions return the inverse hyperbolic tangent of x.
37
38       If x is a NaN, a NaN is returned.
39
40       If x is +0 (-0), +0 (-0) is returned.
41
42       If x is +1 or -1,  a  pole  error  occurs,  and  the  functions  return
43       HUGE_VAL,  HUGE_VALF,  or  HUGE_VALL, respectively, with the mathemati‐
44       cally correct sign.
45
46       If the absolute value of x is greater than 1, a  domain  error  occurs,
47       and a NaN is returned.
48

ERRORS

50       See  math_error(7) for information on how to determine whether an error
51       has occurred when calling these functions.
52
53       The following errors can occur:
54
55       Domain error: x less than -1 or greater than +1
56              errno is set  to  EDOM.   An  invalid  floating-point  exception
57              (FE_INVALID) is raised.
58
59       Pole error: x is +1 or -1
60              errno  is set to ERANGE (but see BUGS).  A divide-by-zero float‐
61              ing-point exception (FE_DIVBYZERO) is raised.
62

ATTRIBUTES

64       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
65       tributes(7).
66
67       ┌────────────────────────────────────────────┬───────────────┬─────────┐
68Interface                                   Attribute     Value   
69       ├────────────────────────────────────────────┼───────────────┼─────────┤
70atanh(), atanhf(), atanhl()                 │ Thread safety │ MT-Safe │
71       └────────────────────────────────────────────┴───────────────┴─────────┘
72

STANDARDS

74       C11, POSIX.1-2008.
75

HISTORY

77       C99, POSIX.1-2001.
78
79       The variant returning double also conforms to SVr4, 4.3BSD.
80

BUGS

82       In  glibc  2.9  and  earlier, when a pole error occurs, errno is set to
83       EDOM instead of the POSIX-mandated ERANGE.   Since  glibc  2.10,  glibc
84       does the right thing.
85

SEE ALSO

87       acosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)
88
89
90
91Linux man-pages 6.04              2023-03-30                          atanh(3)
Impressum