---
title: nan
framework: swift
role: symbol
role_heading: Type Property
path: swift/float16/nan
---

# nan

A quiet NaN (“not a number”).

## Declaration

```swift
static var nan: Float16 { get }
```

## Discussion

Discussion A NaN compares not equal, not greater than, and not less than every value, including itself. Passing a NaN to an operation generally results in NaN. let x = 1.21 // x > Double.nan == false // x < Double.nan == false // x == Double.nan == false Because a NaN always compares not equal to itself, to test whether a floating-point value is NaN, use its isNaN property instead of the equal-to operator (==). In the following example, y is NaN. let y = x + Double.nan print(y == Double.nan) // Prints "false" print(y.isNaN) // Prints "true"