atanh(3m) - osol9

1atanh(3M)               Mathematical Library Functions               atanh(3M)
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NAME

6       atanh, atanhf, atanhl - inverse hyperbolic tangent functions
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SYNOPSIS

9       c99 [ flag... ] file... -lm [ library... ]
10       #include <math.h>
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12       double atanh(double x);
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15       float atanhf(float x);
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18       long double atanhl(long double x);
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DESCRIPTION

22       These  functions  compute the inverse hyperbolic tangent of their argu‐
23       ment x.
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RETURN VALUES

26       Upon successful completion, these functions return the  inverse  hyper‐
27       bolic tangent of their argument.
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30       If  x  is  ±1,  a pole error occurs and atanh(), atanhf(), and atanhl()
31       return the value of  the  macro  HUGE_VAL,  HUGE_VALF,  and  HUGE_VALL,
32       respectively, with the same sign as the correct value of the function.
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35       For finite |x| > 1, a domain error occurs and a NaN is returned.
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38       If x is NaN, NaN is returned.
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41       If x is +0, x is returned.
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44       If x is +Inf, a domain error occurs and a NaN is returned.
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47       For  exceptional cases, matherr(3M) tabulates the values to be returned
48       by atanh() as specified by SVID3 and XPG3.
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ERRORS

51       These functions will fail if:
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53       Domain Error    The x argument is finite and not in the  range  [-1,1],
54                       or is ±Inf.
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56                       If   the   integer   expression   (math_errhandling   &
57                       MATH_ERREXCEPT) is non-zero, the invalid floating-point
58                       exception is raised.
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60                       The atanh() function sets errno to EDOM if the absolute
61                       value of x is greater than 1.0.
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64       Pole Error      The x argument is ±1.
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66                       If   the   integer   expression   (math_errhandling   &
67                       MATH_ERREXCEPT)  is  non-zero,  then the divide-by-zero
68                       floating-point exception is raised.
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70                       The atanh() function sets errno to ERANGE if the  abso‐
71                       lute value of x is equal to 1.0.
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USAGE

75       An  application  wanting to check for exceptions should call feclearex‐
76       cept(FE_ALL_EXCEPT) before  calling  these  functions.  On  return,  if
77       fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
78       non-zero, an exception has been raised. An  application  should  either
79       examine the return value or check the floating point exception flags to
80       detect exceptions.
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83       An application can also set errno  to  0  before  calling  atanh().  On
84       return,  if  errno is non-zero, an error has occurred. The atanhf() and
85       atanhl() functions do not set errno.
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ATTRIBUTES

88       See attributes(5) for descriptions of the following attributes:
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93       ┌─────────────────────────────┬─────────────────────────────┐
94       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
95       ├─────────────────────────────┼─────────────────────────────┤
96       │Interface Stability          │Standard                     │
97       ├─────────────────────────────┼─────────────────────────────┤
98       │MT-Level                     │MT-Safe                      │
99       └─────────────────────────────┴─────────────────────────────┘
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