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 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 .nf
  49     cosh(x) = (exp(x) + exp(\-x)) / 2
  50 .fi
  51 .SH RETURN VALUE
  52 On success, these functions return the hyperbolic cosine of
  53 .IR x .
  54 .PP
  55 If
  56 .I x
  57 is a NaN, a NaN is returned.
  58 .PP
  59 If
  60 .I x
  61 is +0 or \-0, 1 is returned.
  62 .PP
  63 If
  64 .I x
  65 is positive infinity or negative infinity,
  66 positive infinity is returned.
  67 .PP
  68 If the result overflows,
  69 a range error occurs,
  70 and the functions return
  71 .RB + HUGE_VAL ,
  72 .RB + HUGE_VALF ,
  73 or
  74 .RB + HUGE_VALL ,
  75 respectively.
  76 .SH ERRORS
  77 See
  78 .BR math_error (7)
  79 for information on how to determine whether an error has occurred
  80 when calling these functions.
  81 .PP
  82 The following errors can occur:
  83 .TP
  84 Range error: result overflow
  85 .I errno
  86 is set to
  87 .BR ERANGE .
  88 An overflow floating-point exception
  89 .RB ( FE_OVERFLOW )
  90 is raised.
  91 .SH ATTRIBUTES
  92 For an explanation of the terms used in this section, see
  93 .BR attributes (7).
  94 .ad l
  95 .nh
  96 .TS
  97 allbox;
  98 lbx lb lb
  99 l l l.
 100 Interface       Attribute       Value
 101 T{
 102 .BR cosh (),
 103 .BR coshf (),
 104 .BR coshl ()
 105 T}      Thread safety   MT-Safe
 106 .TE
 107 .hy
 108 .ad
 109 .sp 1
 110 .SH CONFORMING TO
 111 C99, POSIX.1-2001, POSIX.1-2008.
 112 .PP
 113 The variant returning
 114 .I double
 115 also conforms to
 116 SVr4, 4.3BSD.
 117 .SH BUGS
 118 In glibc version 2.3.4 and earlier,
 119 an overflow floating-point
 120 .RB ( FE_OVERFLOW  )
 121 exception is not raised when an overflow occurs.
 122 .SH SEE ALSO
 123 .BR acosh (3),
 124 .BR asinh (3),
 125 .BR atanh (3),
 126 .BR ccos (3),
 127 .BR sinh (3),
 128 .BR tanh (3)