acos(3p) - f35

1ACOS(3P)                   POSIX Programmer's Manual                  ACOS(3P)
2
3
4

PROLOG

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.
10

NAME

12       acos, acosf, acosl — arc cosine functions
13

SYNOPSIS

15       #include <math.h>
16
17       double acos(double x);
18       float acosf(float x);
19       long double acosl(long double x);
20

DESCRIPTION

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.
26
27       These  functions shall compute the principal value of the arc cosine of
28       their argument x.  The value of x should be in the range [-1,1].
29
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.
35

RETURN VALUE

37       Upon successful completion, these functions shall return the arc cosine
38       of x, in the range [0,π] radians.
39
40       For  finite  values  of x not in the range [-1,1], a domain error shall
41       occur, and either a NaN (if supported),  or  an  implementation-defined
42       value shall be returned.
43
44       If x is NaN, a NaN shall be returned.
45
46       If x is +1, +0 shall be returned.
47
48       If x is ±Inf, a domain error shall occur, and a NaN shall be returned.
49

ERRORS

51       These functions shall fail if:
52
53       Domain Error
54                   The x argument is finite and is not in the range [-1,1], or
55                   is ±Inf.
56
57                   If the integer expression (math_errhandling  &  MATH_ERRNO)
58                   is  non-zero,  then  errno  shall be set to [EDOM].  If the
59                   integer expression (math_errhandling &  MATH_ERREXCEPT)  is
60                   non-zero,  then  the invalid floating-point exception shall
61                   be raised.
62
63       The following sections are informative.
64

EXAMPLES

66       None.
67

APPLICATION USAGE

69       On  error,  the  expressions  (math_errhandling   &   MATH_ERRNO)   and
70       (math_errhandling  & MATH_ERREXCEPT) are independent of each other, but
71       at least one of them must be non-zero.
72

RATIONALE

74       None.
75

FUTURE DIRECTIONS

77       None.
78

COPYRIGHT

86       Portions  of  this text are reprinted and reproduced in electronic form
87       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
88       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
89       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
90       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
91       event of any discrepancy between this version and the original IEEE and
92       The  Open Group Standard, the original IEEE and The Open Group Standard
93       is the referee document. The original Standard can be  obtained  online
94       at http://www.opengroup.org/unix/online.html .
95
96       Any  typographical  or  formatting  errors that appear in this page are
97       most likely to have been introduced during the conversion of the source
98       files  to  man page format. To report such errors, see https://www.ker‐
99       nel.org/doc/man-pages/reporting_bugs.html .
100
101
102
103IEEE/The Open Group                  2017                             ACOS(3P)