AlgoDeterminant.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.advanced;

import org.geogebra.common.kernel.Construction;
import org.geogebra.common.kernel.algos.AlgoElement;
import org.geogebra.common.kernel.commands.Commands;
import org.geogebra.common.kernel.geos.GeoElement;
import org.geogebra.common.kernel.geos.GeoList;
import org.geogebra.common.kernel.geos.GeoNumeric;
import org.geogebra.common.util.GgbMat;

/**
 * Reverse a list. Adapted from AlgoSort
 * 
 * @author Michael Borcherds
 * @version 16-02-2008
 */

public class AlgoDeterminant extends AlgoElement {

	private GeoList inputList; // input
	private GeoNumeric num; // output

	public AlgoDeterminant(Construction cons, String label, GeoList inputList) {
		super(cons);
		this.inputList = inputList;

		num = new GeoNumeric(cons);

		setInputOutput();
		compute();
		num.setLabel(label);
	}

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

	@Override
	protected void setInputOutput() {
		input = new GeoElement[1];
		input[0] = inputList;

		super.setOutputLength(1);
		super.setOutput(0, num);
		setDependencies(); // done by AlgoElement
	}

	public GeoNumeric getResult() {
		return num;
	}

	@Override
	public final void compute() {

		GgbMat matrix = new GgbMat(inputList);

		if (matrix.isUndefined() || !matrix.isSquare()) {
			num.setUndefined();
			return;
		}

		double det = matrix.determinant();

		if (matrix.hasOnlyIntegers()) {
			det = Math.round(det);
		}

		num.setValue(det);

		// Determinant[{{1,2},{3,4}}]
	}

}