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   2015-04-19 "" "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 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
  60 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
  61 _POSIX_C_SOURCE\ >=\ 200112L;
  62 .br
  63 or
  64 .I cc\ -std=c99
  65 .RE
  66 .br
  67 .BR acoshf (),
  68 .BR acoshl ():
  69 .RS 4
  70 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
  71 _POSIX_C_SOURCE\ >=\ 200112L;
  72 .br
  73 or
  74 .I cc\ -std=c99
  75 .RE
  76 .ad b
  77 .SH DESCRIPTION
  78 These functions calculate the inverse hyperbolic cosine of
  79 .IR x ;
  80 that is the value whose hyperbolic cosine is
  81 .IR x .
  82 .SH RETURN VALUE
  83 On success, these functions return the inverse hyperbolic cosine of
  84 .IR x .
  85
  86 If
  87 .I x
  88 is a NaN, a NaN is returned.
  89
  90 If
  91 .I x
  92 is +1, +0 is returned.
  93
  94 If
  95 .I x
  96 is positive infinity, positive infinity is returned.
  97
  98 If
  99 .I x
 100 is less than 1,
 101 a domain error occurs,
 102 and the functions return a NaN.
 103 .SH ERRORS
 104 See
 105 .BR math_error (7)
 106 for information on how to determine whether an error has occurred
 107 when calling these functions.
 108 .PP
 109 The following errors can occur:
 110 .TP
 111 Domain error: \fIx\fP is less than 1
 112 .I errno
 113 is set to
 114 .BR EDOM .
 115 An invalid floating-point exception
 116 .RB ( FE_INVALID )
 117 is raised.
 118 .SH ATTRIBUTES
 119 For an explanation of the terms used in this section, see
 120 .BR attributes (7).
 121 .TS
 122 allbox;
 123 lbw28 lb lb
 124 l l l.
 125 Interface       Attribute       Value
 126 T{
 127 .BR acosh (),
 128 .BR acoshf (),
 129 .BR acoshl ()
 130 T}      Thread safety   MT-Safe
 131 .TE
 132 .SH CONFORMING TO
 133 C99, POSIX.1-2001, POSIX.1-2008.
 134
 135 The variant returning
 136 .I double
 137 also conforms to
 138 SVr4, 4.3BSD, C89.
 139 .SH SEE ALSO
 140 .BR asinh (3),
 141 .BR atanh (3),
 142 .BR cacosh (3),
 143 .BR cosh (3),
 144 .BR sinh (3),
 145 .BR tanh (3)