# Swift - acosh() Function

The Swift acosh() function returns inverse hyperbolic cosine of a value. The inverse hyperbolic cosine of x is defined as:

### Syntax

In Foundation framework, it is defined as follows:

```public func acosh(_ x: CGFloat) -> CGFloat
public func acosh(_ x: Float) -> Float
public func acosh(_ x: Float80) -> Float80
public func acosh(_ __x: Double) -> Double
```

### Parameters

 `x` Specify the value equal to or greater than 1.0.

### Return Value

Returns the inverse hyperbolic cosine of a value.
If the x is less than 1.0, it returns -nan.

### Example:

In the example below, acosh() function is used to find out the hyperbolic cosine of a value.

```import Foundation

print("acosh(0.0) = \(acosh(0.0))")
print("acosh(2.0) = \(acosh(2.0))")
print("acosh(4.0) = \(acosh(4.0))")
print("acosh(8.0) = \(acosh(8.0))")
```

The output of the above code will be:

```acosh(0.0) = -nan
acosh(2.0) = 1.3169578969248166
acosh(4.0) = 2.0634370688955608
acosh(8.0) = 2.7686593833135738
```

❮ Swift Math Functions

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