1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
3 .\" <mtk.manpages@gmail.com>
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15 .\" Since the Linux kernel and libraries are constantly changing, this
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27 .\" References consulted:
28 .\" Linux libc source code
29 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
31 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
32 .\" Modified 2002-07-25 by Walter Harms
33 .\" (walter.harms@informatik.uni-oldenburg.de)
35 .TH ACOS 3 2010-09-20 "" "Linux Programmer's Manual"
37 acos, acosf, acosl \- arc cosine function
42 .BI "double acos(double " x );
43 .BI "float acosf(float " x );
44 .BI "long double acosl(long double " x );
50 Feature Test Macro Requirements for glibc (see
51 .BR feature_test_macros (7)):
58 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
59 _POSIX_C_SOURCE\ >=\ 200112L;
68 function calculates the arc cosine of
71 the value whose cosine is
74 On success, these functions return the arc cosine of
76 in radians; the return value is in the range [0,\ pi].
80 is a NaN, a NaN is returned.
89 is positive infinity or negative infinity,
90 a domain error occurs,
91 and a NaN is returned.
95 is outside the range [\-1,\ 1],
96 a domain error occurs,
97 and a NaN is returned.
101 for information on how to determine whether an error has occurred
102 when calling these functions.
104 The following errors can occur:
106 Domain error: \fIx\fP is outside the range [\-1,\ 1]
110 An invalid floating-point exception
115 The variant returning