man3/acos.3

   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>
   4 .\"
   5 .\" %%%LICENSE_START(VERBATIM)
   6 .\" Permission is granted to make and distribute verbatim copies of this
   7 .\" manual provided the copyright notice and this permission notice are
   8 .\" preserved on all copies.
   9 .\"
  10 .\" Permission is granted to copy and distribute modified versions of this
  11 .\" manual under the conditions for verbatim copying, provided that the
  12 .\" entire resulting derived work is distributed under the terms of a
  13 .\" permission notice identical to this one.
  14 .\"
  15 .\" Since the Linux kernel and libraries are constantly changing, this
  16 .\" manual page may be incorrect or out-of-date.  The author(s) assume no
  17 .\" responsibility for errors or omissions, or for damages resulting from
  18 .\" the use of the information contained herein.  The author(s) may not
  19 .\" have taken the same level of care in the production of this manual,
  20 .\" which is licensed free of charge, as they might when working
  21 .\" professionally.
  22 .\"
  23 .\" Formatted or processed versions of this manual, if unaccompanied by
  24 .\" the source, must acknowledge the copyright and authors of this work.
  25 .\" %%%LICENSE_END
  26 .\"
  27 .\" References consulted:
  28 .\"     Linux libc source code
  29 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  30 .\"     386BSD man pages
  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)
  34 .\"
  35 .TH ACOS 3  2017-09-15 "" "Linux Programmer's Manual"
  36 .SH NAME
  37 acos, acosf, acosl \- arc cosine function
  38 .SH SYNOPSIS
  39 .nf
  40 .B #include <math.h>
  41 .PP
  42 .BI "double acos(double " x );
  43 .BI "float acosf(float " x );
  44 .BI "long double acosl(long double " x );
  45 .fi
  46 .PP
  47 Link with \fI\-lm\fP.
  48 .PP
  49 .in -4n
  50 Feature Test Macro Requirements for glibc (see
  51 .BR feature_test_macros (7)):
  52 .in
  53 .PP
  54 .ad l
  55 .BR acosf (),
  56 .BR acosl ():
  57 .RS 4
  58 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  59     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  60     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  61 .RE
  62 .ad b
  63 .SH DESCRIPTION
  64 These functions calculate the arc cosine of
  65 .IR x ;
  66 that is
  67 the value whose cosine is
  68 .IR x .
  69 .SH RETURN VALUE
  70 On success, these functions return the arc cosine of
  71 .IR x
  72 in radians; the return value is in the range [0,\ pi].
  73 .PP
  74 If
  75 .I x
  76 is a NaN, a NaN is returned.
  77 .PP
  78 If
  79 .I x
  80 is +1,
  81 +0 is returned.
  82 .PP
  83 If
  84 .I x
  85 is positive infinity or negative infinity,
  86 a domain error occurs,
  87 and a NaN is returned.
  88 .PP
  89 If
  90 .I x
  91 is outside the range [\-1,\ 1],
  92 a domain error occurs,
  93 and a NaN is returned.
  94 .SH ERRORS
  95 See
  96 .BR math_error (7)
  97 for information on how to determine whether an error has occurred
  98 when calling these functions.
  99 .PP
 100 The following errors can occur:
 101 .TP
 102 Domain error: \fIx\fP is outside the range [\-1,\ 1]
 103 .I errno
 104 is set to
 105 .BR EDOM .
 106 An invalid floating-point exception
 107 .RB ( FE_INVALID )
 108 is raised.
 109 .SH ATTRIBUTES
 110 For an explanation of the terms used in this section, see
 111 .BR attributes (7).
 112 .TS
 113 allbox;
 114 lbw24 lb lb
 115 l l l.
 116 Interface       Attribute       Value
 117 T{
 118 .BR acos (),
 119 .BR acosf (),
 120 .BR acosl ()
 121 T}      Thread safety   MT-Safe
 122 .TE
 123 .SH CONFORMING TO
 124 C99, POSIX.1-2001, POSIX.1-2008.
 125 .PP
 126 The variant returning
 127 .I double
 128 also conforms to
 129 SVr4, 4.3BSD, C89.
 130 .SH SEE ALSO
 131 .BR asin (3),
 132 .BR atan (3),
 133 .BR atan2 (3),
 134 .BR cacos (3),
 135 .BR cos (3),
 136 .BR sin (3),
 137 .BR tan (3)