/*
* 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.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package org.encog.mathutil.rbf;
import org.encog.mathutil.BoundMath;
/**
* Multi-dimensional Inverse Multiquadric function.
*
*/
public class InverseMultiquadricFunction extends BasicRBF {
/**
* Serial id.
*/
private static final long serialVersionUID = 1L;
/**
* Construct a single-dimension Inverse-Multiquadric function with the
* specified peak, centers and widths.
*
* @param peak
* The peak for all dimensions.
* @param center
* The centers for each dimension.
* @param width
* The widths for each dimension.
*/
public InverseMultiquadricFunction(final double center, final double peak,
final double width) {
setCenters(new double[1]);
getCenters()[0] = center;
setPeak(peak);
setWidth(width);
}
/**
* Construct a multi-dimension Inverse-Multiquadric function with the
* specified peak, centers and widths.
*
* @param peak
* The peak for all dimensions.
* @param center
* The centers for each dimension.
* @param width
* The widths for each dimension.
*/
public InverseMultiquadricFunction(final double peak,
final double[] center, final double width) {
setCenters(center);
setPeak(peak);
setWidth(width);
}
/**
* Create centered at zero, width 0, and peak 0.
*
* @param dimensions
* The dimensions.
*/
public InverseMultiquadricFunction(final int dimensions) {
setCenters(new double[dimensions]);
setPeak(1.0);
setWidth(1.0);
}
/**
* {@inheritDoc}
*/
@Override
public final double calculate(final double[] x) {
double value = 0;
final double[] center = getCenters();
final double width = getWidth();
for (int i = 0; i < center.length; i++) {
value += Math.pow(x[i] - center[i], 2) + (width * width);
}
return getPeak() / BoundMath.sqrt(value);
}
}