man3/cosh.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 1996-06-08 by aeb
  33 .\" Modified 2002-07-27 by Walter Harms
  34 .\" (walter.harms@informatik.uni-oldenburg.de)
  35 .\"
  36 .TH COSH 3 2015-03-02 ""  "Linux Programmer's Manual"
  37 .SH NAME
  38 cosh, coshf, coshl \- hyperbolic cosine function
  39 .SH SYNOPSIS
  40 .nf
  41 .B #include <math.h>
  42 .sp
  43 .BI "double cosh(double " x );
  44 .br
  45 .BI "float coshf(float " x );
  46 .br
  47 .BI "long double coshl(long double " x );
  48 .fi
  49 .sp
  50 Link with \fI\-lm\fP.
  51 .sp
  52 .in -4n
  53 Feature Test Macro Requirements for glibc (see
  54 .BR feature_test_macros (7)):
  55 .in
  56 .sp
  57 .ad l
  58 .BR coshf (),
  59 .BR coshl ():
  60 .RS 4
  61 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
  62 _POSIX_C_SOURCE\ >=\ 200112L;
  63 .br
  64 or
  65 .I cc\ -std=c99
  66 .RE
  67 .ad
  68 .SH DESCRIPTION
  69 These functions return the hyperbolic cosine of
  70 .IR x ,
  71 which is defined mathematically as:
  72 .nf
  73
  74     cosh(x) = (exp(x) + exp(\-x)) / 2
  75 .fi
  76 .SH RETURN VALUE
  77 On success, these functions return the hyperbolic cosine of
  78 .IR x .
  79
  80 If
  81 .I x
  82 is a NaN, a NaN is returned.
  83
  84 If
  85 .I x
  86 is +0 or \-0, 1 is returned.
  87
  88 If
  89 .I x
  90 is positive infinity or negative infinity,
  91 positive infinity is returned.
  92
  93 If the result overflows,
  94 a range error occurs,
  95 and the functions return
  96 .RB + HUGE_VAL ,
  97 .RB + HUGE_VALF ,
  98 or
  99 .RB + HUGE_VALL ,
 100 respectively.
 101 .SH ERRORS
 102 See
 103 .BR math_error (7)
 104 for information on how to determine whether an error has occurred
 105 when calling these functions.
 106 .PP
 107 The following errors can occur:
 108 .TP
 109 Range error: result overflow
 110 .I errno
 111 is set to
 112 .BR ERANGE .
 113 An overflow floating-point exception
 114 .RB ( FE_OVERFLOW )
 115 is raised.
 116 .SH ATTRIBUTES
 117 For an explanation of the terms used in this section, see
 118 .BR attributes (7).
 119 .TS
 120 allbox;
 121 lbw24 lb lb
 122 l l l.
 123 Interface       Attribute       Value
 124 T{
 125 .BR cosh (),
 126 .BR coshf (),
 127 .BR coshl ()
 128 T}      Thread safety   MT-Safe
 129 .TE
 130 .SH CONFORMING TO
 131 C99, POSIX.1-2001, POSIX.1-2008.
 132
 133 The variant returning
 134 .I double
 135 also conforms to
 136 SVr4, 4.3BSD.
 137 .SH BUGS
 138 In glibc version 2.3.4 and earlier,
 139 an overflow floating-point
 140 .RB ( FE_OVERFLOW  )
 141 exception is not raised when an overflow occurs.
 142 .SH SEE ALSO
 143 .BR acosh (3),
 144 .BR asinh (3),
 145 .BR atanh (3),
 146 .BR ccos (3),
 147 .BR sinh (3),
 148 .BR tanh (3)