# Swift - log2() Function

The Swift log2() function returns the base-2 logarithm of a given number.

### Syntax

In Foundation framework, it is defined as follows:

```public func log2(_ x: CGFloat) -> CGFloat
public func log2(_ x: Float) -> Float
public func log2(_ x: Float80) -> Float80
public func log2(_ __x: Double) -> Double
```

### Parameters

 `x` Specify the number.

### Return Value

Returns the base-2 logarithm 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, log2() function is used to calculate the base-2 logarithm of a given number.

```import Foundation

print("log2(0.0) = \(log2(0.0))")
print("log2(1.0) = \(log2(1.0))")
print("log2(2.0) = \(log2(2.0))")
print("log2(50.0) = \(log2(50.0))")
print("log2(-1.0) = \(log2(-1.0))")
```

The output of the above code will be:

```log2(0.0) = -inf
log2(1.0) = 0.0
log2(2.0) = 1.0
log2(50.0) = 5.643856189774724
log2(-1.0) = -nan
```

❮ Swift Math Functions

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