# BNNS.PoolingType Constants that describe pooling types. ``` enum PoolingType ``` ## Topics ### Pooling Types [`case average(countIncludesPadding: Bool)`](/documentation/Accelerate/BNNS/PoolingType/average(countIncludesPadding:)) A function for pooling that computes the average of each element in the pooling kernel. [`case l2Norm`](/documentation/Accelerate/BNNS/PoolingType/l2Norm) A function for pooling that computes the square root of the sum of squares of each element in the pooling kernel. [`case max(indices: UnsafeMutableBufferPointer?, xDilationStride: Int, yDilationStride: Int)`](/documentation/Accelerate/BNNS/PoolingType/max(indices:xDilationStride:yDilationStride:)) A function for pooling that computes the maximum of each element in the pooling kernel. [`case unMax(indices: UnsafeMutableBufferPointer?, xDilationStride: Int, yDilationStride: Int)`](/documentation/Accelerate/BNNS/PoolingType/unMax(indices:xDilationStride:yDilationStride:)) A function for pooling that’s the partial inverse of max pooling and sets all nonmaximal values to zero. ### Instance Properties [`var bnnsPoolingFunction: BNNSPoolingFunction`](/documentation/Accelerate/BNNS/PoolingType/bnnsPoolingFunction) The underlying pooling function structure. ### Enumeration Cases [`case maxEx(indicesDescriptor: BNNSNDArrayDescriptor?, xDilationStride: Int, yDilationStride: Int)`](/documentation/Accelerate/BNNS/PoolingType/maxEx(indicesDescriptor:xDilationStride:yDilationStride:)) [`case unMaxEx(indicesDescriptor: BNNSNDArrayDescriptor, xDilationStride: Int, yDilationStride: Int)`](/documentation/Accelerate/BNNS/PoolingType/unMaxEx(indicesDescriptor:xDilationStride:yDilationStride:)) --- Copyright © 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)