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>
   4 .\"
   5 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   6 .\"
   7 .\" References consulted:
   8 .\"     Linux libc source code
   9 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  10 .\"     386BSD man pages
  11 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  12 .\" Modified 1996-06-08 by aeb
  13 .\" Modified 2002-07-27 by Walter Harms
  14 .\" (walter.harms@informatik.uni-oldenburg.de)
  15 .\"
  16 .TH COSH 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
  17 .SH NAME
  18 cosh, coshf, coshl \- hyperbolic cosine function
  19 .SH LIBRARY
  20 Math library
  21 .RI ( libm ", " \-lm )
  22 .SH SYNOPSIS
  23 .nf
  24 .B #include <math.h>
  25 .PP
  26 .BI "double cosh(double " x );
  27 .BI "float coshf(float " x );
  28 .BI "long double coshl(long double " x );
  29 .fi
  30 .PP
  31 .RS -4
  32 Feature Test Macro Requirements for glibc (see
  33 .BR feature_test_macros (7)):
  34 .RE
  35 .PP
  36 .BR coshf (),
  37 .BR coshl ():
  38 .nf
  39     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  40         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  41         || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  42 .fi
  43 .SH DESCRIPTION
  44 These functions return the hyperbolic cosine of
  45 .IR x ,
  46 which is defined mathematically as:
  47 .PP
  48 .in +4n
  49 .EX
  50 cosh(x) = (exp(x) + exp(\-x)) / 2
  51 .EE
  52 .in
  53 .SH RETURN VALUE
  54 On success, these functions return the hyperbolic cosine of
  55 .IR x .
  56 .PP
  57 If
  58 .I x
  59 is a NaN, a NaN is returned.
  60 .PP
  61 If
  62 .I x
  63 is +0 or \-0, 1 is returned.
  64 .PP
  65 If
  66 .I x
  67 is positive infinity or negative infinity,
  68 positive infinity is returned.
  69 .PP
  70 If the result overflows,
  71 a range error occurs,
  72 and the functions return
  73 .RB + HUGE_VAL ,
  74 .RB + HUGE_VALF ,
  75 or
  76 .RB + HUGE_VALL ,
  77 respectively.
  78 .SH ERRORS
  79 See
  80 .BR math_error (7)
  81 for information on how to determine whether an error has occurred
  82 when calling these functions.
  83 .PP
  84 The following errors can occur:
  85 .TP
  86 Range error: result overflow
  87 .I errno
  88 is set to
  89 .BR ERANGE .
  90 An overflow floating-point exception
  91 .RB ( FE_OVERFLOW )
  92 is raised.
  93 .SH ATTRIBUTES
  94 For an explanation of the terms used in this section, see
  95 .BR attributes (7).
  96 .ad l
  97 .nh
  98 .TS
  99 allbox;
 100 lbx lb lb
 101 l l l.
 102 Interface       Attribute       Value
 103 T{
 104 .BR cosh (),
 105 .BR coshf (),
 106 .BR coshl ()
 107 T}      Thread safety   MT-Safe
 108 .TE
 109 .hy
 110 .ad
 111 .sp 1
 112 .SH STANDARDS
 113 C99, POSIX.1-2001, POSIX.1-2008.
 114 .PP
 115 The variant returning
 116 .I double
 117 also conforms to
 118 SVr4, 4.3BSD.
 119 .SH BUGS
 120 In glibc version 2.3.4 and earlier,
 121 an overflow floating-point
 122 .RB ( FE_OVERFLOW  )
 123 exception is not raised when an overflow occurs.
 124 .SH SEE ALSO
 125 .BR acosh (3),
 126 .BR asinh (3),
 127 .BR atanh (3),
 128 .BR ccos (3),
 129 .BR sinh (3),
 130 .BR tanh (3)