acosf(3m) - osol9

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

6       acos, acosf, acosl - arc cosine functions
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SYNOPSIS

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

22       These functions compute the principal value of the arc cosine of x. The
23       value of x should be in the range [−1,1].
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RETURN VALUES

26       Upon successful completion, these functions return the arc cosine of  x
27       in the range [0, pi] radians.
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30       For  finite values of  x not in the range [−1,1], a domain error occurs
31       and NaN is returned.
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34       If x is NaN, NaN is returned.
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37       If x is +1, +0 is returned.
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40       If x is ±Inf, a domain error occurs and NaN is returned.
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43       For exceptional cases, matherr(3M) tabulates the values to be  returned
44       by acos() as specified by SVID3 and XPG3.
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ERRORS

47       These functions will fail if:
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49       Domain Error    The  x  argument is finite and not in the range [-1,1],
50                       or is ±Inf.
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52                       If   the   integer   expression   (math_errhandling   &
53                       MATH_ERREXCEPT) is non-zero, the invalid floating-point
54                       exception is raised.
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56                       The acos() function sets errno to EDOM if x is not ±Inf
57                       or NaN and is not in the range [−1,1].
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USAGE

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

74       See attributes(5) for descriptions of the following attributes:
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79       ┌─────────────────────────────┬─────────────────────────────┐
80       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
81       ├─────────────────────────────┼─────────────────────────────┤
82       │Interface Stability          │Standard                     │
83       ├─────────────────────────────┼─────────────────────────────┤
84       │MT-Level                     │MT-Safe                      │
85       └─────────────────────────────┴─────────────────────────────┘
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