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   2017-09-15 "" "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 .PP
  42 .BI "double acosh(double " x );
  43 .BI "float acoshf(float " x );
  44 .BI "long double acoshl(long double " x );
  45 .PP
  46 .fi
  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 acosh ():
  56 .RS 4
  57 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  58     || _XOPEN_SOURCE\ >=\ 500
  59 .\"    || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
  60     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  61     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  62 .RE
  63 .br
  64 .BR acoshf (),
  65 .BR acoshl ():
  66 .RS 4
  67 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  68     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  69     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  70 .RE
  71 .ad b
  72 .SH DESCRIPTION
  73 These functions calculate the inverse hyperbolic cosine of
  74 .IR x ;
  75 that is the value whose hyperbolic cosine is
  76 .IR x .
  77 .SH RETURN VALUE
  78 On success, these functions return the inverse hyperbolic cosine of
  79 .IR x .
  80 .PP
  81 If
  82 .I x
  83 is a NaN, a NaN is returned.
  84 .PP
  85 If
  86 .I x
  87 is +1, +0 is returned.
  88 .PP
  89 If
  90 .I x
  91 is positive infinity, positive infinity is returned.
  92 .PP
  93 If
  94 .I x
  95 is less than 1,
  96 a domain error occurs,
  97 and the functions return a NaN.
  98 .SH ERRORS
  99 See
 100 .BR math_error (7)
 101 for information on how to determine whether an error has occurred
 102 when calling these functions.
 103 .PP
 104 The following errors can occur:
 105 .TP
 106 Domain error: \fIx\fP is less than 1
 107 .I errno
 108 is set to
 109 .BR EDOM .
 110 An invalid floating-point exception
 111 .RB ( FE_INVALID )
 112 is raised.
 113 .SH ATTRIBUTES
 114 For an explanation of the terms used in this section, see
 115 .BR attributes (7).
 116 .TS
 117 allbox;
 118 lbw28 lb lb
 119 l l l.
 120 Interface       Attribute       Value
 121 T{
 122 .BR acosh (),
 123 .BR acoshf (),
 124 .BR acoshl ()
 125 T}      Thread safety   MT-Safe
 126 .TE
 127 .SH CONFORMING TO
 128 C99, POSIX.1-2001, POSIX.1-2008.
 129 .PP
 130 The variant returning
 131 .I double
 132 also conforms to
 133 SVr4, 4.3BSD.
 134 .SH SEE ALSO
 135 .BR asinh (3),
 136 .BR atanh (3),
 137 .BR cacosh (3),
 138 .BR cosh (3),
 139 .BR sinh (3),
 140 .BR tanh (3)