# Swift - log() Function

The Swift log() function returns the natural logarithm (base-e) of a given number.

### Syntax

In Foundation framework, it is defined as follows:

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

### Parameters

 `x` Specify the number.

### Return Value

Returns the natural logarithm (base-e) of a given number.
If the x is negative, it returns -nan.
If the x is 0, it returns -inf.

### Example:

In the example below, log() function is used to calculate the natural logarithm (base-e) of a given number.

```import Foundation

print("log(0.0) = \(log(0.0))")
print("log(1.0) = \(log(1.0))")
print("log(M_E) = \(log(M_E))")
print("log(50.0) = \(log(50.0))")
print("log(-1.0) = \(log(-1.0))")
```

The output of the above code will be:

```log(0.0) = -inf
log(1.0) = 0.0
log(M_E) = 1.0
log(50.0) = 3.912023005428146
log(-1.0) = -nan
```

❮ Swift Math Functions

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