AlgoRandomBinomial.java

/* 
GeoGebra - Dynamic Mathematics for Everyone
http://www.geogebra.org

This file is part of GeoGebra.

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.

 */

package org.geogebra.common.kernel.statistics;

import org.geogebra.common.kernel.Construction;
import org.geogebra.common.kernel.Kernel;
import org.geogebra.common.kernel.SetRandomValue;
import org.geogebra.common.kernel.algos.AlgoTwoNumFunction;
import org.geogebra.common.kernel.commands.Commands;
import org.geogebra.common.kernel.geos.GeoNumberValue;

/**
 * Computes RandomNormal[a, b]
 * 
 * @author Michael Borcherds
 */
public class AlgoRandomBinomial extends AlgoTwoNumFunction
		implements SetRandomValue {

	public AlgoRandomBinomial(Construction cons, String label, GeoNumberValue a,
			GeoNumberValue b) {
		super(cons, label, a, b);

		// output is random number
		cons.addRandomGeo(num);
	}

	@Override
	public Commands getClassName() {
		return Commands.RandomBinomial;
	}

	@Override
	public final void compute() {
		// int frac[] = {0,0};
		// int [] frac = DecimalToFraction(b.getDouble(),0.00000001);
		// Application.debug(frac[0]+" "+frac[1]);

		if (input[0].isDefined() && input[1].isDefined()) {
			if (b.getDouble() < 0) {
				num.setUndefined();
			} else {
				// disabled randomBinomialTRS() as it doesn't work well
				// eg when p is near 0.5
				// http://www.geogebra.org/forum/viewtopic.php?f=8&t=18685
				// num.setValue(randomBinomialTRS((int)a.getDouble(),
				// b.getDouble()));
				num.setValue(
						randomBinomial((int) a.getDouble(), b.getDouble()));
			}

		} else {
			num.setUndefined();
		}
	}

	@Override
	public void setRandomValue(double d0) {
		double d = Math.round(Kernel.checkInteger(d0));

		if (d >= 0 && d <= a.getDouble()) {
			num.setValue(d);
			num.updateRepaint();
		}

	}

	private int randomBinomial(double n, double p) {

		int count = 0;
		for (int i = 0; i < n; i++) {
			if (kernel.getApplication().getRandomNumber() < p) {
				count++;
			}
		}

		return count;

	}

	// private static double halflog2pi = 0.5 * Math.log(2 * Math.PI);

	// private static double logtable[] = new double[10];

	// private int[] DecimalToFraction(double Decimal, double AccuracyFactor) {
	// double FractionNumerator, FractionDenominator;
	// double DecimalSign;
	// double Z;
	// double PreviousDenominator;
	// double ScratchValue;
	//
	// int ret[] = {0,0};
	// if (Decimal < 0.0) DecimalSign = -1.0; else DecimalSign = 1.0;
	// Decimal = Math.abs(Decimal);
	// if (Decimal == Math.floor(Decimal)) { // handles exact integers including
	// 0
	// FractionNumerator = Decimal * DecimalSign;
	// FractionDenominator = 1.0;
	// ret[0] = (int)FractionNumerator;
	// ret[1] = (int)FractionDenominator;
	// return ret;
	// }
	// if (Decimal < 1.0E-19) { // X = 0 already taken care of
	// FractionNumerator = DecimalSign;
	// FractionDenominator = 9999999999999999999.0;
	// ret[0] = (int)FractionNumerator;
	// ret[1] = (int)FractionDenominator;
	// return ret;
	// }
	// if (Decimal > 1.0E19) {
	// FractionNumerator = 9999999999999999999.0*DecimalSign;
	// FractionDenominator = 1.0;
	// ret[0] = (int)FractionNumerator;
	// ret[1] = (int)FractionDenominator;
	// return ret;
	// }
	// Z = Decimal;
	// PreviousDenominator = 0.0;
	// FractionDenominator = 1.0;
	// do {
	// Z = 1.0/(Z - Math.floor(Z));
	// ScratchValue = FractionDenominator;
	// FractionDenominator = FractionDenominator * Math.floor(Z) +
	// PreviousDenominator;
	// PreviousDenominator = ScratchValue;
	// FractionNumerator = Math.floor(Decimal * FractionDenominator + 0.5); //
	// Rounding Function
	// } while ( Math.abs((Decimal - (FractionNumerator /FractionDenominator)))
	// > AccuracyFactor && Z != Math.floor(Z));
	// FractionNumerator = DecimalSign*FractionNumerator;
	//
	// ret[0] = (int)FractionNumerator;
	// ret[1] = (int)FractionDenominator;
	// return ret;
	// }

}