acosh(3m) - osol9

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

6       acosh, acoshf, acoshl - inverse hyperbolic cosine functions
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SYNOPSIS

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

22       These functions compute the inverse hyperbolic cosine of their argument
23       x.
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RETURN VALUES

26       Upon successful completion, these functions return the  inverse  hyper‐
27       bolic cosine of their argument.
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30       For finite values of  x < 1, a domain error occurs and NaN is returned.
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33       If x is NaN, NaN is returned.
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36       If x is +1, +0 is returned.
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39       If x is +Inf, +Inf is returned.
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42       If x is −Inf, a domain error occurs and NaN is returned.
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45       For  exceptional cases, matherr(3M) tabulates the values to be returned
46       by acosh() as specified by SVID3 and XPG3.
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ERRORS

49       These functions will fail if:
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51       Domain Error    The x argument is finite and less than 1.0, or is −Inf.
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53                       If   the   integer   expression   (math_errhandling   &
54                       MATH_ERREXCEPT) is non-zero, the invalid floating-point
55                       exception is raised.
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57                       The acosh() function sets errno to EDOM if  x  is  less
58                       than 1.0.
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USAGE

62       An  application  wanting to check for exceptions should call feclearex‐
63       cept(FE_ALL_EXCEPT) before  calling  these  functions.  On  return,  if
64       fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
65       non-zero, an exception has been raised. An  application  should  either
66       examine the return value or check the floating point exception flags to
67       detect exceptions.
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70       An application can also set errno  to  0  before  calling  acosh().  On
71       return,  if  errno is non-zero, an error has occurred. The acoshf() and
72       acoshl() functions do not set errno.
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ATTRIBUTES

75       See attributes(5) for descriptions of the following attributes:
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80       ┌─────────────────────────────┬─────────────────────────────┐
81       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
82       ├─────────────────────────────┼─────────────────────────────┤
83       │Interface Stability          │Standard                     │
84       ├─────────────────────────────┼─────────────────────────────┤
85       │MT-Level                     │MT-Safe                      │
86       └─────────────────────────────┴─────────────────────────────┘
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