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 2017-09-15 ""  "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 .PP
  43 .BI "double cosh(double " x );
  44 .BI "float coshf(float " x );
  45 .BI "long double coshl(long double " x );
  46 .fi
  47 .PP
  48 Link with \fI\-lm\fP.
  49 .PP
  50 .in -4n
  51 Feature Test Macro Requirements for glibc (see
  52 .BR feature_test_macros (7)):
  53 .in
  54 .PP
  55 .ad l
  56 .BR coshf (),
  57 .BR coshl ():
  58 .RS 4
  59 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  60     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  61     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  62 .RE
  63 .ad
  64 .SH DESCRIPTION
  65 These functions return the hyperbolic cosine of
  66 .IR x ,
  67 which is defined mathematically as:
  68 .PP
  69 .nf
  70     cosh(x) = (exp(x) + exp(\-x)) / 2
  71 .fi
  72 .SH RETURN VALUE
  73 On success, these functions return the hyperbolic cosine of
  74 .IR x .
  75 .PP
  76 If
  77 .I x
  78 is a NaN, a NaN is returned.
  79 .PP
  80 If
  81 .I x
  82 is +0 or \-0, 1 is returned.
  83 .PP
  84 If
  85 .I x
  86 is positive infinity or negative infinity,
  87 positive infinity is returned.
  88 .PP
  89 If the result overflows,
  90 a range error occurs,
  91 and the functions return
  92 .RB + HUGE_VAL ,
  93 .RB + HUGE_VALF ,
  94 or
  95 .RB + HUGE_VALL ,
  96 respectively.
  97 .SH ERRORS
  98 See
  99 .BR math_error (7)
 100 for information on how to determine whether an error has occurred
 101 when calling these functions.
 102 .PP
 103 The following errors can occur:
 104 .TP
 105 Range error: result overflow
 106 .I errno
 107 is set to
 108 .BR ERANGE .
 109 An overflow floating-point exception
 110 .RB ( FE_OVERFLOW )
 111 is raised.
 112 .SH ATTRIBUTES
 113 For an explanation of the terms used in this section, see
 114 .BR attributes (7).
 115 .TS
 116 allbox;
 117 lbw24 lb lb
 118 l l l.
 119 Interface       Attribute       Value
 120 T{
 121 .BR cosh (),
 122 .BR coshf (),
 123 .BR coshl ()
 124 T}      Thread safety   MT-Safe
 125 .TE
 126 .SH CONFORMING TO
 127 C99, POSIX.1-2001, POSIX.1-2008.
 128 .PP
 129 The variant returning
 130 .I double
 131 also conforms to
 132 SVr4, 4.3BSD.
 133 .SH BUGS
 134 In glibc version 2.3.4 and earlier,
 135 an overflow floating-point
 136 .RB ( FE_OVERFLOW  )
 137 exception is not raised when an overflow occurs.
 138 .SH SEE ALSO
 139 .BR acosh (3),
 140 .BR asinh (3),
 141 .BR atanh (3),
 142 .BR ccos (3),
 143 .BR sinh (3),
 144 .BR tanh (3)