---
title: permutation
framework: accelerate
role: symbol
role_heading: Instance Property
path: accelerate/bnnslayerparameterspermute/permutation
---

# permutation

The tuple that defines the permutation.

## Declaration

```swift
var permutation: (Int, Int, Int, Int, Int, Int, Int, Int)
```

## Discussion

Discussion Use the permutation array to specify the input axis source for the corresponding output axis source. For example, a permutation array [2,1,0] applied on a BNNSDataLayoutImageCHW tensor results in axis reverse (that is, output axis 0 is input axis 2, output axis 1 is input axis 1, and output axis 2 is input axis 0).

## See Also

### Instance Properties

- [i_desc](accelerate/bnnslayerparameterspermute/i_desc.md)
- [o_desc](accelerate/bnnslayerparameterspermute/o_desc.md)