annotate src/samer/maths/random/BoundedHyperbolic.java @ 8:5e3cbbf173aa tip

Reorganise some more

/*
 *	Copyright (c) 2000, Samer Abdallah, King's College London.
 *	All rights reserved.
 *
 *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
 *	without even the implied warranty of MERCHANTABILITY or 
 *	FITNESS FOR A PARTICULAR PURPOSE.
 */

package samer.maths.random;
import  samer.core.types.*;
import  java.util.*;

/*
 *		Hyperbolic distribution: power law with exponent 1.
 *		Integral of pdf diverges in both directions, so we
 *		need both upper and lower cut-offs.
 */
public class BoundedHyperbolic extends BaseRandom implements Observer
{
	VDouble min = new VDouble("min",1);
	VDouble max = new VDouble("max",2);
	double  a, b;

	public void dispose() { min.dispose(); max.dispose(); }
	public double next() { return b*Math.exp(a*rnd.nextDouble()); }

	public BoundedHyperbolic( double min, double max) 
	{
		this();
		this.min.value = min; this.min.changed();
		this.max.value = max; this.max.changed();
	}

	public BoundedHyperbolic() 
	{
		min.addObserver(this);
		max.addObserver(this);
		update(null,null);
	}

	public void update(Observable o, Object oo) {
		a=Math.log(min.value/max.value); 
		b=max.value;
	}
}