# COSH

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

ATTRIBUTES

CONFORMING TO

BUGS

SEE ALSO

COLOPHON

## NAME

cosh, coshf,
coshl − hyperbolic cosine function

## SYNOPSIS

**#include
<math.h>**

**double
cosh(double** *x***); **

float coshf(float *x***); **

long double coshl(long double *x***);**

Link with
*−lm*.

Feature Test
Macro Requirements for glibc (see
**feature_test_macros**(7)):

**coshf**(),
**coshl**():

_BSD_SOURCE || _SVID_SOURCE ||
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;

or *cc -std=c99*

## DESCRIPTION

The
**cosh**() function returns the hyperbolic cosine of
*x*, which is defined mathematically as:

cosh(x) =
(exp(x) + exp(−x)) / 2

## RETURN VALUE

On success,
these functions return the hyperbolic cosine of
*x*.

If *x* is
a NaN, a NaN is returned.

If *x* is
+0 or −0, 1 is returned.

If *x* is
positive infinity or negative infinity, positive infinity is
returned.

If the result
overflows, a range error occurs, and the functions return
+**HUGE_VAL**, +**HUGE_VALF**, or +**HUGE_VALL**,
respectively.

## ERRORS

See
**math_error**(7) for information on how to determine
whether an error has occurred when calling these
functions.

The following
errors can occur:

Range error: result overflow

*errno* is set to
**ERANGE**. An overflow floating-point exception
(**FE_OVERFLOW**) is raised.

## ATTRIBUTES

For an
explanation of the terms used in this section, see
**attributes**(7).

## CONFORMING TO

C99,
POSIX.1-2001. The variant returning *double* also
conforms to SVr4, 4.3BSD.

## BUGS

In glibc
version 2.3.4 and earlier, an overflow floating-point
(**FE_OVERFLOW**) exception is not raised when an
overflow occurs.

## SEE ALSO

**acosh**(3),
**asinh**(3), **atanh**(3), **ccos**(3),
**sinh**(3), **tanh**(3)

## COLOPHON

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part of release 3.53 of the Linux *man-pages* project.
A description of the project, and information about
reporting bugs, can be found at
http://www.kernel.org/doc/man−pages/.