/*
* VonMisesDistribution.java
*
* Copyright (c) 2002-2015 Alexei Drummond, Andrew Rambaut and Marc Suchard
*
* This file is part of BEAST.
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership and licensing.
*
* BEAST is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* BEAST 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with BEAST; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
package dr.geo.distributions;
import cern.jet.math.Bessel;
import dr.geo.math.Space;
/**
* @author Marc Suchard
*/
public class VonMisesDistribution extends HyperSphereDistribution {
public VonMisesDistribution(int dim, Space space, double[] mean, double kappa) {
super(dim, space, mean, kappa);
}
public double logPdf(double[] x) {
return logPdf(x, mean, kappa, space);
}
public String getType() {
return "von Mises";
}
protected int getAllowableDim() {
return 2;
}
private static double logNormalizationConstant(double kappa) {
return -LOG_2_PI - Math.log(Bessel.i0(kappa));
}
public static double logPdf(double[] x, double[] mean, double kappa, Space space) {
return logNormalizationConstant(kappa) + kappa * HyperSphereDistribution.innerProduct(x, mean, space);
}
public static void main(String[] arg) {
// Test in radians
double kappa = 2;
double[] mean = { 1 };
double[] x = { -4 };
System.err.println("logP = "+logPdf(x, mean, kappa, Space.RADIANS)+" ?= -2.094546");
}
}