# cosh()

Returns the hyperbolic cosine of a double value.

## Syntax

`Numeric cosh()`

## Usage

The hyperbolic cosine of `x` is defined to be (e`x` +
e-`x`)/2 where e is Euler's number.

Special cases:

- If the value is NaN, then the result is NaN.
- If the value is infinite, then the result is positive infinity.
- If the value is zero, then the result is 1.0.

The computed result must be within 2.5 ulps of the exact result.