leakyrelu

Apply leaky rectified linear unit activation

Syntax

Y = leakyrelu(X)

Y = leakyrelu(X,scaleFactor)

Description

The leaky rectified linear unit (ReLU) activation operation performs a nonlinear threshold operation, where any input value less than zero is multiplied by a fixed scale factor.

This operation is equivalent to

$$f(x)=\{\begin{array}{ll}x,\hfill & x\ge 0\hfill \\ scale*x,\hfill & x<0\hfill \end{array}.$$

Note

This function applies the leaky ReLU operation to dlarray data. If you want to apply leaky ReLU activation within a dlnetwork object, use leakyReluLayer.

Y = leakyrelu(X) computes the leaky ReLU activation of the input X by applying a threshold operation. All values in X less than zero are multiplied by a default scale factor of 0.01.

Y = leakyrelu(X,scaleFactor) specifies the scale factor for the leaky ReLU operation.

Examples

Apply Leaky ReLU Operation

Create a formatted dlarray object containing a batch of 128 28-by-28 images with 3 channels. Specify the format 'SSCB' (spatial, spatial, channel, batch).

miniBatchSize = 128;
inputSize = [28 28];
numChannels = 3;
X = rand(inputSize(1),inputSize(2),numChannels,miniBatchSize);
X = dlarray(X,"SSCB");

View the size and format of the input data.

size(X)

ans = 1×4

    28    28     3   128

dims(X)

ans = 
'SSCB'

Apply the leaky ReLU operation using the leakyrelu function.

Y = leakyrelu(X);

View the size and format of the output.

size(Y)

ans = 1×4

    28    28     3   128

dims(Y)

ans = 
'SSCB'

Specify Leaky ReLU Scale

Create a formatted dlarray object containing a batch of 128 28-by-28 images with 3 channels. Specify the format 'SSCB' (spatial, spatial, channel, batch).

miniBatchSize = 128;
inputSize = [28 28];
numChannels = 3;
X = rand(inputSize(1),inputSize(2),numChannels,miniBatchSize);
X = dlarray(X,"SSCB");

View the size and format of the input data.

size(X)

ans = 1×4

    28    28     3   128

dims(X)

ans = 
'SSCB'

Apply the leaky ReLU operation using the leakyrelu function and specify a scale of 0.5.

Y = leakyrelu(X,0.5);

View the size and format of the output.

size(Y)

ans = 1×4

    28    28     3   128

dims(Y)

ans = 
'SSCB'

Input Arguments

X — Input data

dlarray object

Input data, specified as a formatted or unformatted dlarray object.

scaleFactor — Scale factor for negative inputs

0.01 (default) | numeric scalar

Scale factor for negative inputs, specified as a numeric scalar. The default value is 0.01.

Data Types: single | double

Output Arguments

Y — Leaky ReLU activations

dlarray

Leaky ReLU activations, returned as a dlarray. The output Y has the same underlying data type as the input X.

If the input data X is a formatted dlarray, Y has the same dimension format as X. If the input data is not a formatted dlarray, Y is an unformatted dlarray with the same dimension order as the input data.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• scaleFactor must be a constant during code generation.

GPU Code Generation

Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Refer to the usage notes and limitations in the C/C++ Code Generation section. The same limitations apply to GPU code generation.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The leakyrelu function supports GPU array input with these usage notes and limitations:

• When the input argument X is a gpuArray or a dlarray with underlying data of type gpuArray, this function runs on the GPU.

For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Version History

Introduced in R2019b