/**
* Copyright 2010 Neuroph Project http://neuroph.sourceforge.net
*
* 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.neuroph.core.input;
import java.io.Serializable;
import java.util.List;
import org.neuroph.core.Connection;
/**
*<pre>
* Neuron's input function. It has two subcomponents:
*
* weightsFunction - which performs operation with input and weight vector
* summingFunction - which performs operation with the resulting vector from weightsFunction
*
* InputFunction implements the following behaviour:
* output = summingFunction(weightsFunction(inputs))
*
* Different neuron input functions can be created by setting different weights and summing functions.
*</pre>
*
* @author Zoran Sevarac <sevarac@gmail.com>
* @see WeightsFunction
* @see SummingFunction
* @see org.neuroph.core.Neuron
*/
public class InputFunction implements Serializable {
/**
* The class fingerprint that is set to indicate serialization
* compatibility with a previous version of the class.
*/
private static final long serialVersionUID = 2L;
/**
* Weights function component of the input function. It performs some
* operation with weights and input vector, and ouputs vector.
*/
private WeightsFunction weightsFunction;
/**
* Summing function component of the input function. It performs some
* summing operation on output vector from weightsFunction and outputs scalar.
*/
private SummingFunction summingFunction;
/**
* Creates an instance of WeightedSum input function by default.
*/
public InputFunction() {
this.weightsFunction = new WeightedInput();
this.summingFunction = new Sum();
}
/**
* Creates an instance of input function with specified weights and summing function
*
* @param weightsFunction
* vector function performs some operation on input and weight
* vector
* @param summingFunction
* scalar function transforms output from VectorFunction to
* scalar
*/
public InputFunction(WeightsFunction weightsFunction, SummingFunction summingFunction) {
this.weightsFunction = weightsFunction;
this.summingFunction = summingFunction;
}
/**
* Returns ouput value of this input function for the given neuron inputs
*
* @param inputConnections
* neuron's input connections
* @return input total net input
*/
public double getOutput(List<Connection> inputConnections) {
double[] inputVector = this.weightsFunction.getOutput(inputConnections);
double output = this.summingFunction.getOutput(inputVector);
return output;
}
/**
* Returns summing function component of this InputFunction
*
* @return summing function
*/
public SummingFunction getSummingFunction() {
return summingFunction;
}
/**
* Returns weights functioncomponent of this InputFunction
*
* @return weights function
*/
public WeightsFunction getWeightsFunction() {
return weightsFunction;
}
}