org.nd4j.linalg.activations.impl.ActivationSigmoid Maven / Gradle / Ivy
package org.nd4j.linalg.activations.impl;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import org.apache.commons.math3.util.Pair;
import org.nd4j.linalg.activations.BaseActivationFunction;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.api.ops.impl.transforms.Sigmoid;
import org.nd4j.linalg.api.ops.impl.transforms.SigmoidDerivative;
import org.nd4j.linalg.factory.Nd4j;
/**
* f(x) = 1 / (1 + exp(-x))
*/
@EqualsAndHashCode
@Getter
public class ActivationSigmoid extends BaseActivationFunction {
@Override
public INDArray getActivation(INDArray in, boolean training) {
Nd4j.getExecutioner().execAndReturn(new Sigmoid(in));
return in;
}
@Override
public Pair backprop(INDArray in, INDArray epsilon) {
INDArray dLdz = Nd4j.getExecutioner().execAndReturn(new SigmoidDerivative(in));
dLdz.muli(epsilon);
return new Pair<>(dLdz, null);
}
@Override
public String toString() {
return "sigmoid";
}
}