man3/acosh.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>
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  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 ACOSH 3   2016-03-15 "" "Linux Programmer's Manual"
  36 .SH NAME
  37 acosh, acoshf, acoshl \- inverse hyperbolic cosine function
  38 .SH SYNOPSIS
  39 .nf
  40 .B #include <math.h>
  41 .sp
  42 .BI "double acosh(double " x );
  43 .br
  44 .BI "float acoshf(float " x );
  45 .br
  46 .BI "long double acoshl(long double " x );
  47 .sp
  48 .fi
  49 Link with \fI\-lm\fP.
  50 .sp
  51 .in -4n
  52 Feature Test Macro Requirements for glibc (see
  53 .BR feature_test_macros (7)):
  54 .in
  55 .sp
  56 .ad l
  57 .BR acosh ():
  58 .RS 4
  59 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  60     || _XOPEN_SOURCE\ >=\ 500
  61 .\"    || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
  62     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  63     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  64 .RE
  65 .br
  66 .BR acoshf (),
  67 .BR acoshl ():
  68 .RS 4
  69 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  70     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  71     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  72 .RE
  73 .ad b
  74 .SH DESCRIPTION
  75 These functions calculate the inverse hyperbolic cosine of
  76 .IR x ;
  77 that is the value whose hyperbolic cosine is
  78 .IR x .
  79 .SH RETURN VALUE
  80 On success, these functions return the inverse hyperbolic cosine of
  81 .IR x .
  82
  83 If
  84 .I x
  85 is a NaN, a NaN is returned.
  86
  87 If
  88 .I x
  89 is +1, +0 is returned.
  90
  91 If
  92 .I x
  93 is positive infinity, positive infinity is returned.
  94
  95 If
  96 .I x
  97 is less than 1,
  98 a domain error occurs,
  99 and the functions return a NaN.
 100 .SH ERRORS
 101 See
 102 .BR math_error (7)
 103 for information on how to determine whether an error has occurred
 104 when calling these functions.
 105 .PP
 106 The following errors can occur:
 107 .TP
 108 Domain error: \fIx\fP is less than 1
 109 .I errno
 110 is set to
 111 .BR EDOM .
 112 An invalid floating-point exception
 113 .RB ( FE_INVALID )
 114 is raised.
 115 .SH ATTRIBUTES
 116 For an explanation of the terms used in this section, see
 117 .BR attributes (7).
 118 .TS
 119 allbox;
 120 lbw28 lb lb
 121 l l l.
 122 Interface       Attribute       Value
 123 T{
 124 .BR acosh (),
 125 .BR acoshf (),
 126 .BR acoshl ()
 127 T}      Thread safety   MT-Safe
 128 .TE
 129 .SH CONFORMING TO
 130 C99, POSIX.1-2001, POSIX.1-2008.
 131
 132 The variant returning
 133 .I double
 134 also conforms to
 135 SVr4, 4.3BSD, C89.
 136 .SH SEE ALSO
 137 .BR asinh (3),
 138 .BR atanh (3),
 139 .BR cacosh (3),
 140 .BR cosh (3),
 141 .BR sinh (3),
 142 .BR tanh (3)