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