---
title: "simd_fast_rsqrt(_:)"
framework: simd
role: symbol
role_heading: Function
path: "simd/simd_fast_rsqrt(_:)-43tvc"
---

# simd_fast_rsqrt(_:)

Returns the fast reciprocal square root of each element in a vector.

## Declaration

```swift
func simd_fast_rsqrt(_ x: Double) -> Double
```

## See Also

### Reciprocal and Reciprocal Square Root Functions

- [recip(_:)](simd/recip(_:)-8b6ef.md)
- [simd_recip(_:)](simd/simd_recip(_:)-7ylz3.md)
- [simd_fast_recip(_:)](simd/simd_fast_recip(_:)-1h1e.md)
- [simd_precise_recip(_:)](simd/simd_precise_recip(_:)-6qb0h.md)
- [rsqrt(_:)](simd/rsqrt(_:)-7h0u6.md)
- [simd_rsqrt(_:)](simd/simd_rsqrt(_:)-4ygr4.md)
- [simd_precise_rsqrt(_:)](simd/simd_precise_rsqrt(_:)-5fl9s.md)