---
title: "isnan(_:)"
framework: simd
role: symbol
role_heading: Function
path: "simd/isnan(_:)-6l7v3"
---

# isnan(_:)

Returns true for each element that is not a number (NaN) in a vector.

## Declaration

```swift
func isnan(_ x: simd_double3) -> simd_long3
```

## See Also

### Classification Functions

- [isfinite(_:)](simd/isfinite(_:)-1s3ji.md)
- [isinf(_:)](simd/isinf(_:)-6gve5.md)
- [isnormal(_:)](simd/isnormal(_:)-8k36k.md)