org.nd4j.linalg.activations.impl.ActivationELU Maven / Gradle / Ivy
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* * This program and the accompanying materials are made available under the
* * terms of the Apache License, Version 2.0 which is available at
* * https://www.apache.org/licenses/LICENSE-2.0.
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* * information regarding copyright ownership.
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* * SPDX-License-Identifier: Apache-2.0
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package org.nd4j.linalg.activations.impl;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import org.nd4j.linalg.activations.BaseActivationFunction;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.api.ops.impl.transforms.gradient.EluBp;
import org.nd4j.linalg.api.ops.impl.transforms.strict.ELU;
import org.nd4j.linalg.factory.Nd4j;
import org.nd4j.common.primitives.Pair;
@EqualsAndHashCode(callSuper = false)
@Getter
public class ActivationELU extends BaseActivationFunction {
public static final double DEFAULT_ALPHA = 1.0;
private double alpha;
public ActivationELU() {
this(DEFAULT_ALPHA);
}
public ActivationELU(double alpha) {
this.alpha = alpha;
}
/*
= alpha * (exp(x) - 1.0); x < 0
f(x)
= x ; x >= 0
*/
@Override
public INDArray getActivation(INDArray in, boolean training) {
return Nd4j.exec(new ELU(in, in, alpha))[0];
}
/*
= alpha * exp(x) ; x < 0
f'(x)
= 1 ; x >= 0
*/
@Override
public Pair backprop(INDArray in, INDArray epsilon) {
assertShape(in, epsilon);
Nd4j.getExecutioner().execAndReturn(new EluBp(in, epsilon, in));
return new Pair<>(in, null);
}
@Override
public String toString() {
return "elu(alpha=" + alpha + ")";
}
}