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# init(function:input:output:filterParameters:)

Returns a new activation layer.

```
convenience init?(function activationFunction: BNNS.ActivationFunction, input: BNNSNDArrayDescriptor, output: BNNSNDArrayDescriptor, filterParameters: BNNSFilterParameters? = nil)
```

## Parameters

`activationFunction`

The activation function that the layer applies to the output.

`input`

The descriptor of the input.

`output`

The descriptor of the output.

`filterParameters`

The filter runtime parameters.

## Discussion

> Important:
> The input dimensions must be equal to the output dimensions. For activation types other than identity, the input and output must be `float`.

---

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