/*
* Encog(tm) Core v3.4 - Java Version
* http://www.heatonresearch.com/encog/
* https://github.com/encog/encog-java-core
* Copyright 2008-2016 Heaton Research, 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.
*
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*/
package org.encog.mathutil.matrices.hessian;
import org.encog.mathutil.matrices.Matrix;
import org.encog.ml.data.MLDataSet;
import org.encog.neural.flat.FlatNetwork;
import org.encog.neural.networks.BasicNetwork;
import org.encog.util.EngineArray;
/**
* Some basic code used to calculate Hessian matrixes.
*/
public abstract class BasicHessian implements ComputeHessian {
/**
* The training data that provides the ideal values.
*/
protected MLDataSet training;
/**
* The neural network that we would like to train.
*/
protected BasicNetwork network;
/**
* The sum of square error.
*/
protected double sse;
/**
* The gradients of the Hessian.
*/
protected double[] gradients;
/**
* The Hessian matrix.
*/
protected Matrix hessianMatrix;
/**
* The Hessian 2d array.
*/
protected double[][] hessian;
/**
* The flat network.
*/
protected FlatNetwork flat;
/**
* {@inheritDoc}
*/
public void init(BasicNetwork theNetwork, MLDataSet theTraining) {
int weightCount = theNetwork.getStructure().getFlat().getWeights().length;
this.flat = theNetwork.getFlat();
this.training = theTraining;
this.network = theNetwork;
this.gradients = new double[weightCount];
this.hessianMatrix = new Matrix(weightCount,weightCount);
this.hessian = this.hessianMatrix.getData();
}
/**
* {@inheritDoc}
*/
public double[] getGradients() {
return gradients;
}
/**
* {@inheritDoc}
*/
public Matrix getHessianMatrix() {
return hessianMatrix;
}
/**
* {@inheritDoc}
*/
public double[][] getHessian() {
return hessian;
}
/**
* {@inheritDoc}
*/
public void clear() {
EngineArray.fill(this.gradients, 0);
this.hessianMatrix.clear();
}
/**
* {@inheritDoc}
*/
public double getSSE() {
return sse;
}
/**
* Update the Hessian, sum's with what is in the Hessian already. Call clear to clear out old Hessian.
* @param d Vector to update with.
*/
public void updateHessian(double[] d) {
// update the hessian
int weightCount = this.network.getFlat().getWeights().length;
for(int i=0;i<weightCount;i++) {
for(int j=0;j<weightCount;j++) {
this.hessian[i][j]+=d[i]*d[j];
}
}
}
}