---
title: "BNNSComputeNormBackward(_:_:_:_:_:_:)"
framework: accelerate
role: symbol
role_heading: Function
path: "accelerate/bnnscomputenormbackward(_:_:_:_:_:_:)"
---

# BNNSComputeNormBackward(_:_:_:_:_:_:)

Backpropogates gradients for the compute norm function.

## Declaration

```swift
func BNNSComputeNormBackward(_ in: UnsafeRawPointer, _ in_delta: UnsafeMutablePointer<BNNSNDArrayDescriptor>, _ out: UnsafeRawPointer, _ out_delta: UnsafePointer<BNNSNDArrayDescriptor>, _ norm_type: BNNSNormType, _ axis_flags: UInt32) -> Int32
```

## Parameters

- `in`: The descriptor of the input.
- `in_delta`: The descriptor of the input delta.
- `out`: The descriptor of the output.
- `out_delta`: The descriptor of the output delta.
- `norm_type`: The type of the norm. This function supports only doc://com.apple.accelerate/documentation/Accelerate/BNNSL2Norm.
- `axis_flags`: The dimensions that the function uses to compute the norm. Set to 0 to specify that the function computes the norm over all dimensions.

## See Also

### Compute norm functions

- [computeNorm(input:output:axes:)](accelerate/bnns/computenorm(input:output:axes:).md)
- [computeNormBackward(input:output:axes:outputGradient:generatingInputGradient:)](accelerate/bnns/computenormbackward(input:output:axes:outputgradient:generatinginputgradient:).md)
- [BNNSComputeNorm(_:_:_:_:)](accelerate/bnnscomputenorm(_:_:_:_:).md)
- [BNNSNormType](accelerate/bnnsnormtype.md)