<!--
{
  "availability" : [

  ],
  "documentType" : "symbol",
  "framework" : "Accelerate",
  "identifier" : "/documentation/simd/simd_fast_length-4okp0",
  "metadataVersion" : "0.1.0",
  "role" : "Function",
  "symbol" : {
    "kind" : "Function",
    "modules" : [
      "simd"
    ],
    "preciseIdentifier" : "c:@F@simd_fast_length#]4d#"
  },
  "title" : "simd_fast_length"
}
-->

# simd_fast_length

Returns the fast length of a vector.

```
static double simd_fast_length(simd_double4 __x);
```

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)