1ATANH(3P) POSIX Programmer's Manual ATANH(3P)
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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
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15 #include <math.h>
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17 double atanh(double x);
18 float atanhf(float x);
19 long double atanhl(long double x);
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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.
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27 These functions shall compute the inverse hyperbolic tangent of their
28 argument x.
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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.
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37 Upon successful completion, these functions shall return the inverse
38 hyperbolic tangent of their argument.
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40 If x is ±1, a pole error shall occur, and atanh(), atanhf(), and
41 atanhl() shall return the value of the macro HUGE_VAL, HUGE_VALF, and
42 HUGE_VALL, respectively, with the same sign as the correct value of the
43 function.
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45 For finite |x|>1, a domain error shall occur, and either a NaN (if sup‐
46 ported), or an implementation-defined value shall be returned.
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48 If x is NaN, a NaN shall be returned.
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50 If x is ±0, x shall be returned.
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52 If x is ±Inf, a domain error shall occur, and a NaN shall be returned.
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54 If x is subnormal, a range error may occur
55 and x should be returned.
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57 If x is not returned, atanh(), atanhf(), and atanhl() shall return an
58 implementation-defined value no greater in magnitude than DBL_MIN,
59 FLT_MIN, and LDBL_MIN, respectively.
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62 These functions shall fail if:
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64 Domain Error
65 The x argument is finite and not in the range [-1,1], or is
66 ±Inf.
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68 If the integer expression (math_errhandling & MATH_ERRNO)
69 is non-zero, then errno shall be set to [EDOM]. If the
70 integer expression (math_errhandling & MATH_ERREXCEPT) is
71 non-zero, then the invalid floating-point exception shall
72 be raised.
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74 Pole Error The x argument is ±1.
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76 If the integer expression (math_errhandling & MATH_ERRNO)
77 is non-zero, then errno shall be set to [ERANGE]. If the
78 integer expression (math_errhandling & MATH_ERREXCEPT) is
79 non-zero, then the divide-by-zero floating-point exception
80 shall be raised.
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82 These functions may fail if:
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84 Range Error The value of x is subnormal.
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86 If the integer expression (math_errhandling & MATH_ERRNO)
87 is non-zero, then errno shall be set to [ERANGE]. If the
88 integer expression (math_errhandling & MATH_ERREXCEPT) is
89 non-zero, then the underflow floating-point exception shall
90 be raised.
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92 The following sections are informative.
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95 None.
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98 On error, the expressions (math_errhandling & MATH_ERRNO) and
99 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
100 at least one of them must be non-zero.
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103 None.
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106 None.
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109 feclearexcept(), fetestexcept(), tanh()
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111 The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
112 Error Conditions for Mathematical Functions, <math.h>
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115 Portions of this text are reprinted and reproduced in electronic form
116 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
117 table Operating System Interface (POSIX), The Open Group Base Specifi‐
118 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
119 Electrical and Electronics Engineers, Inc and The Open Group. In the
120 event of any discrepancy between this version and the original IEEE and
121 The Open Group Standard, the original IEEE and The Open Group Standard
122 is the referee document. The original Standard can be obtained online
123 at http://www.opengroup.org/unix/online.html .
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125 Any typographical or formatting errors that appear in this page are
126 most likely to have been introduced during the conversion of the source
127 files to man page format. To report such errors, see https://www.ker‐
128 nel.org/doc/man-pages/reporting_bugs.html .
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132IEEE/The Open Group 2017 ATANH(3P)