---
title: "copyBandPart(_:to:lowerBandCount:upperBandCount:filterParameters:)"
framework: accelerate
role: symbol
role_heading: Type Method
path: "accelerate/bnns/copybandpart(_:to:lowerbandcount:upperbandcount:filterparameters:)"
---

# copyBandPart(_:to:lowerBandCount:upperBandCount:filterParameters:)

Copies the specified subdiagonals and superdiagonals of a matrix, and sets other elements to zero.

## Declaration

```swift
static func copyBandPart(_ source: BNNSNDArrayDescriptor, to destination: BNNSNDArrayDescriptor, lowerBandCount: Int?, upperBandCount: Int?, filterParameters: BNNSFilterParameters? = nil) throws
```

## Parameters

- `source`: The input descriptor.
- `destination`: The output descriptor.
- `lowerBandCount`: The number of subdiagonals that the function copies. Set to nil to copy the entire lower triangle.
- `upperBandCount`: The number of superdiagonals that the function copies. Set to nil to copy the entire upper triangle.
- `filterParameters`: The filter runtime parameters.

## See Also

### Related Documentation

- [BNNSBandPart(_:_:_:_:_:)](accelerate/bnnsbandpart(_:_:_:_:_:).md)

### Utility functions

- [copy(_:to:filterParameters:)](accelerate/bnns/copy(_:to:filterparameters:).md)
- [transpose(input:output:firstTransposeAxis:secondTransposeAxis:filterParameters:)](accelerate/bnns/transpose(input:output:firsttransposeaxis:secondtransposeaxis:filterparameters:).md)
- [BNNSCopy(_:_:_:)](accelerate/bnnscopy(_:_:_:).md)
- [BNNSTranspose(_:_:_:_:_:)](accelerate/bnnstranspose(_:_:_:_:_:).md)
- [BNNSGetPointer(_:_:)](accelerate/bnnsgetpointer(_:_:).md)
- [BNNSPointerSpecifier](accelerate/bnnspointerspecifier.md)
- [BNNS.GramLayer](accelerate/bnns/gramlayer.md)
- [BNNSLayerParametersGram](accelerate/bnnslayerparametersgram.md)
- [BNNSFilterCreateLayerGram(_:_:)](accelerate/bnnsfiltercreatelayergram(_:_:).md)
- [clip(to:input:output:)](accelerate/bnns/clip(to:input:output:).md)
- [clipByNorm(threshold:input:output:axes:)](accelerate/bnns/clipbynorm(threshold:input:output:axes:).md)
- [clipByGlobalNorm(threshold:inputs:outputs:globalNorm:)](accelerate/bnns/clipbyglobalnorm(threshold:inputs:outputs:globalnorm:).md)
- [BNNSClipByValue(_:_:_:_:)](accelerate/bnnsclipbyvalue(_:_:_:_:).md)
- [BNNSClipByNorm(_:_:_:_:)](accelerate/bnnsclipbynorm(_:_:_:_:).md)
- [BNNSClipByGlobalNorm(_:_:_:_:_:)](accelerate/bnnsclipbyglobalnorm(_:_:_:_:_:).md)