1ATANH(3P) POSIX Programmer's Manual ATANH(3P)
2
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.
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12 atanh, atanhf, atanhl - inverse hyperbolic tangent functions
13
15 #include <math.h>
16 double atanh(double x);
18 float atanhf(float x);
19 long double atanhl(long double x);
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23 These functions shall compute the inverse hyperbolic tangent of their
24 argument x.
25 An application wishing to check for error situations should set errno
27 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
28 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID
29 | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
30 occurred.
31
33 Upon successful completion, these functions shall return the inverse
34 hyperbolic tangent of their argument.
35 If x is ±1, a pole error shall occur, and atanh(), atanhf(), and
37 atanhl() shall return the value of the macro HUGE_VAL, HUGE_VALF, and
38 HUGE_VALL, respectively, with the same sign as the correct value of the
39 function.
40 For finite |x|>1, a domain error shall occur, and either a NaN (if
42 supported), or an implementation-defined value shall be returned.
43 If x is NaN, a NaN shall be returned.
45 If x is ±0, x shall be returned.
47 If x is ±Inf, a domain error shall occur, and either a NaN (if sup‐
49 ported), or an implementation-defined value shall be returned.
50 If x is subnormal, a range error may occur and x should be returned.
52
54 These functions shall fail if:
55 Domain Error
57 The x argument is finite and not in the range [-1,1], or is
58 ±Inf.
59 If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
61 then errno shall be set to [EDOM]. If the integer expression
62 (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid
63 floating-point exception shall be raised.
64 Pole Error
66 The x argument is ±1.
67 If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
69 then errno shall be set to [ERANGE]. If the integer expression
70 (math_errhandling & MATH_ERREXCEPT) is non-zero, then the divide-by-
71 zero floating-point exception shall be raised.
72 These functions may fail if:
76 Range Error
78 The value of x is subnormal.
79 If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
81 then errno shall be set to [ERANGE]. If the integer expression
82 (math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow
83 floating-point exception shall be raised.
84 The following sections are informative.
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89 None.
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92 On error, the expressions (math_errhandling & MATH_ERRNO) and
93 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
94 at least one of them must be non-zero.
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97 None.
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100 None.
101
103 feclearexcept(), fetestexcept(), tanh(), the Base Definitions volume of
104 IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions for
105 Mathematical Functions, <math.h>
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108 Portions of this text are reprinted and reproduced in electronic form
109 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
110 -- Portable Operating System Interface (POSIX), The Open Group Base
111 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
112 Electrical and Electronics Engineers, Inc and The Open Group. In the
113 event of any discrepancy between this version and the original IEEE and
114 The Open Group Standard, the original IEEE and The Open Group Standard
115 is the referee document. The original Standard can be obtained online
116 at http://www.opengroup.org/unix/online.html .
117IEEE/The Open Group 2003 ATANH(3P)