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 2015-04-19 ""  "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 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  62     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  63     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  64 .br
  65 or
  66 .I cc\ -std=c99
  67 .RE
  68 .ad
  69 .SH DESCRIPTION
  70 These functions return the hyperbolic cosine of
  71 .IR x ,
  72 which is defined mathematically as:
  73 .nf
  74
  75     cosh(x) = (exp(x) + exp(\-x)) / 2
  76 .fi
  77 .SH RETURN VALUE
  78 On success, these functions return the hyperbolic cosine of
  79 .IR x .
  80
  81 If
  82 .I x
  83 is a NaN, a NaN is returned.
  84
  85 If
  86 .I x
  87 is +0 or \-0, 1 is returned.
  88
  89 If
  90 .I x
  91 is positive infinity or negative infinity,
  92 positive infinity is returned.
  93
  94 If the result overflows,
  95 a range error occurs,
  96 and the functions return
  97 .RB + HUGE_VAL ,
  98 .RB + HUGE_VALF ,
  99 or
 100 .RB + HUGE_VALL ,
 101 respectively.
 102 .SH ERRORS
 103 See
 104 .BR math_error (7)
 105 for information on how to determine whether an error has occurred
 106 when calling these functions.
 107 .PP
 108 The following errors can occur:
 109 .TP
 110 Range error: result overflow
 111 .I errno
 112 is set to
 113 .BR ERANGE .
 114 An overflow floating-point exception
 115 .RB ( FE_OVERFLOW )
 116 is raised.
 117 .SH ATTRIBUTES
 118 For an explanation of the terms used in this section, see
 119 .BR attributes (7).
 120 .TS
 121 allbox;
 122 lbw24 lb lb
 123 l l l.
 124 Interface       Attribute       Value
 125 T{
 126 .BR cosh (),
 127 .BR coshf (),
 128 .BR coshl ()
 129 T}      Thread safety   MT-Safe
 130 .TE
 131 .SH CONFORMING TO
 132 C99, POSIX.1-2001, POSIX.1-2008.
 133
 134 The variant returning
 135 .I double
 136 also conforms to
 137 SVr4, 4.3BSD.
 138 .SH BUGS
 139 In glibc version 2.3.4 and earlier,
 140 an overflow floating-point
 141 .RB ( FE_OVERFLOW  )
 142 exception is not raised when an overflow occurs.
 143 .SH SEE ALSO
 144 .BR acosh (3),
 145 .BR asinh (3),
 146 .BR atanh (3),
 147 .BR ccos (3),
 148 .BR sinh (3),
 149 .BR tanh (3)