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org.nd4j.linalg.api.ops.impl.transforms.SigmoidDerivative Maven / Gradle / Ivy
/*-
*
* * Copyright 2015 Skymind,Inc.
* *
* * Licensed under the Apache License, Version 2.0 (the "License");
* * you may not use this file except in compliance with the License.
* * You may obtain a copy of the License at
* *
* * http://www.apache.org/licenses/LICENSE-2.0
* *
* * Unless required by applicable law or agreed to in writing, software
* * distributed under the License is distributed on an "AS IS" BASIS,
* * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* * See the License for the specific language governing permissions and
* * limitations under the License.
*
*
*/
package org.nd4j.linalg.api.ops.impl.transforms;
import org.apache.commons.math3.util.FastMath;
import org.nd4j.linalg.api.complex.IComplexDouble;
import org.nd4j.linalg.api.complex.IComplexNumber;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.api.ops.BaseTransformOp;
import org.nd4j.linalg.api.ops.Op;
import org.nd4j.linalg.factory.Nd4j;
/**
* Sigmoid derivative
*
* @author Adam Gibson
*/
public class SigmoidDerivative extends BaseTransformOp {
public SigmoidDerivative() {}
public SigmoidDerivative(INDArray x, INDArray z) {
super(x, z);
}
public SigmoidDerivative(INDArray x, INDArray z, long n) {
super(x, z, n);
}
public SigmoidDerivative(INDArray x, INDArray y, INDArray z, long n) {
super(x, y, z, n);
}
public SigmoidDerivative(INDArray x) {
super(x);
}
@Override
public int opNum() {
return 29;
}
@Override
public String name() {
return "sigmoidderivative";
}
@Override
public IComplexNumber op(IComplexNumber origin, double other) {
return sigmoidDeriv(origin);
}
@Override
public IComplexNumber op(IComplexNumber origin, float other) {
return sigmoidDeriv(origin);
}
@Override
public IComplexNumber op(IComplexNumber origin, IComplexNumber other) {
return sigmoidDeriv(origin);
}
@Override
public float op(float origin, float other) {
return (float) sigmoidDeriv(origin);
}
@Override
public double op(double origin, double other) {
return sigmoidDeriv(origin);
}
@Override
public double op(double origin) {
return sigmoidDeriv(origin);
}
@Override
public float op(float origin) {
return (float) sigmoidDeriv(origin);
}
@Override
public IComplexNumber op(IComplexNumber origin) {
return sigmoidDeriv(origin);
}
@Override
public Op opForDimension(int index, int dimension) {
INDArray xAlongDimension = x.vectorAlongDimension(index, dimension);
if (y() != null)
return new SigmoidDerivative(x.vectorAlongDimension(index, dimension),
y.vectorAlongDimension(index, dimension), z.vectorAlongDimension(index, dimension),
xAlongDimension.length());
else
return new SigmoidDerivative(x.vectorAlongDimension(index, dimension),
z.vectorAlongDimension(index, dimension), xAlongDimension.length());
}
@Override
public Op opForDimension(int index, int... dimension) {
INDArray xAlongDimension = x.tensorAlongDimension(index, dimension);
if (y() != null)
return new SigmoidDerivative(x.tensorAlongDimension(index, dimension),
y.tensorAlongDimension(index, dimension), z.tensorAlongDimension(index, dimension),
xAlongDimension.length());
else
return new SigmoidDerivative(x.tensorAlongDimension(index, dimension),
z.tensorAlongDimension(index, dimension), xAlongDimension.length());
}
private static double sigmoidDeriv(double input) {
double sigmoid = 1 / (1 + FastMath.exp(-input));
double out = sigmoid * (1.0 - sigmoid);
if (Nd4j.ENFORCE_NUMERICAL_STABILITY && (Double.isNaN(out) || Double.isInfinite(out))) {
out = Nd4j.EPS_THRESHOLD;
}
return out;
}
private static IComplexNumber sigmoidDeriv(IComplexNumber number) {
double arg = number.complexArgument().doubleValue();
double sigArg = 1 / 1 + (FastMath.exp(-arg)) - 1 + .5f;
double ret = Math.exp(sigArg);
IComplexDouble sigmoid = Nd4j.createDouble(ret, 0);
IComplexNumber oneMinus = Nd4j.createComplexNumber(1, 1).subi(sigmoid);
return sigmoid.mul(oneMinus);
}
}