/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* ActivationLinear.java
* Copyright (C) 2009-2010 Aristotle University of Thessaloniki, Thessaloniki, Greece
*/
package mulan.classifier.neural.model;
/**
* Implements the linear activation function. The input is simply passed to the output.
* This activation function is commonly used for input units of networks, which serves
* as a place holders for input pattern and forwards them for processing.
*
* @author Jozef Vilcek
*/
public class ActivationLinear extends ActivationFunction {
private static final long serialVersionUID = 4255801421493489832L;
public double activate(final double input) {
return input;
}
public double derivative(final double input) {
throw new UnsupportedOperationException("Can't compute a derivative of the linear activation function.");
}
public double getMax() {
return Double.POSITIVE_INFINITY;
}
public double getMin() {
return Double.NEGATIVE_INFINITY;
}
}