.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
.\" Modified 1996-06-08 by aeb
.\" Modified 2002-07-27 by Walter Harms
.\" (walter.harms@informatik.uni-oldenburg.de)
.\"
.TH COSH 3 2017-09-15 ""  "Linux Programmer's Manual"
.SH NAME
cosh, coshf, coshl \- hyperbolic cosine function
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "double cosh(double " x );
.BI "float coshf(float " x );
.BI "long double coshl(long double " x );
.fi
.PP
Link with \fI\-lm\fP.
.PP
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.PP
.ad l
.BR coshf (),
.BR coshl ():
.RS 4
_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.RE
.ad
.SH DESCRIPTION
These functions return the hyperbolic cosine of
.IR x ,
which is defined mathematically as:
.PP
.nf
    cosh(x) = (exp(x) + exp(\-x)) / 2
.fi
.SH RETURN VALUE
On success, these functions return the hyperbolic cosine of
.IR x .
.PP
If
.I x
is a NaN, a NaN is returned.
.PP
If
.I x
is +0 or \-0, 1 is returned.
.PP
If
.I x
is positive infinity or negative infinity,
positive infinity is returned.
.PP
If the result overflows,
a range error occurs,
and the functions return
.RB + HUGE_VAL ,
.RB + HUGE_VALF ,
or
.RB + HUGE_VALL ,
respectively.
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
Range error: result overflow
.I errno
is set to
.BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw24 lb lb
l l l.
Interface	Attribute	Value
T{
.BR cosh (),
.BR coshf (),
.BR coshl ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.PP
The variant returning
.I double
also conforms to
SVr4, 4.3BSD.
.SH BUGS
In glibc version 2.3.4 and earlier,
an overflow floating-point
.RB ( FE_OVERFLOW  )
exception is not raised when an overflow occurs.
.SH SEE ALSO
.BR acosh (3),
.BR asinh (3),
.BR atanh (3),
.BR ccos (3),
.BR sinh (3),
.BR tanh (3)
.SH COLOPHON
This page is part of release 4.16 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.