JavaNN/src/main/java/ActivationLayer.java

import org.ejml.simple.SimpleMatrix;

import java.util.function.Function;

public class ActivationLayer extends Layer {
    Function<SimpleMatrix, SimpleMatrix> activation;
    Function<SimpleMatrix, SimpleMatrix> activationPrime;

    public ActivationLayer(Function<SimpleMatrix, SimpleMatrix> activation, Function<SimpleMatrix, SimpleMatrix> activationPrime) {
        this.activation = activation;
        this.activationPrime = activationPrime;
    }

    @Override
    public SimpleMatrix forwardPropagation(SimpleMatrix input) {
        this.input = input;
        this.output = activation.apply(input);
        return this.output;
    }

    @Override
    public SimpleMatrix backwardPropagation(SimpleMatrix outputError, double learningRate) {
        return activationPrime.apply(this.input).elementMult(outputError);
    }
}