001/* Demo for a signal plotter.
002
003 @Copyright (c) 1997-2014 The Regents of the University of California.
004 All rights reserved.
005
006 Permission is hereby granted, without written agreement and without
007 license or royalty fees, to use, copy, modify, and distribute this
008 software and its documentation for any purpose, provided that the
009 above copyright notice and the following two paragraphs appear in all
010 copies of this software.
011
012 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
013 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
014 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
015 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
016 SUCH DAMAGE.
017
018 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
019 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
020 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
021 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
022 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
023 ENHANCEMENTS, OR MODIFICATIONS.
024
025 PT_COPYRIGHT_VERSION_2
026 COPYRIGHTENDKEY
027 */
028package ptolemy.plot.demo;
029
030import ptolemy.plot.Plot;
031import ptolemy.plot.PlotApplet;
032
033///////////////////////////////////////////////////////////////////
034//// PlotFourierSeries
035
036/**
037 Plot a Fourier series approximation to a square wave.
038 This is a demonstration of the use of the Plot class.
039
040 @author Edward A. Lee
041 @version $Id$
042 @since Ptolemy II 0.2
043 @Pt.ProposedRating red (eal)
044 @Pt.AcceptedRating red (cxh)
045 */
046@SuppressWarnings("serial")
047public class PlotFourierSeries extends PlotApplet {
048    ///////////////////////////////////////////////////////////////////
049    ////                         public methods                    ////
050
051    /**
052     * Return a string describing this applet.
053     */
054    @Override
055    public String getAppletInfo() {
056        return "PlotFourierSeries 1.1: Demo of PlotApplet.\n"
057                + "By: Edward A. Lee\n " + "($Id$)";
058    }
059
060    /**
061     * Initialize the applet.
062     */
063    @Override
064    public void init() {
065        super.init();
066
067        Plot plot = (Plot) plot();
068
069        plot.setTitle("Fourier Series Approximation to a Square Wave");
070        plot.setXRange(0, 400);
071        plot.setMarksStyle("none");
072        plot.addLegend(0, "ideal");
073        plot.addLegend(1, "1 sinusoid");
074
075        for (int j = 2; j <= 10; j++) {
076            plot.addLegend(j, j + " sinusoids");
077        }
078
079        boolean first = true;
080        plot.addPoint(0, 0.0, 0.0, false);
081
082        for (int i = 0; i <= 400; i++) {
083            double approximation = 0.0;
084
085            for (int j = 1; j <= 10; j++) {
086                double sig = 4.0
087                        * Math.sin(i * 2.0 * Math.PI * (2 * j - 1) / 400.0)
088                        / (Math.PI * (2 * j - 1));
089                approximation += sig;
090                plot.addPoint(j, i, approximation, !first);
091            }
092
093            first = false;
094
095            if (i <= 200) {
096                plot.addPoint(0, i, 1.0, true);
097            }
098
099            if (i >= 200) {
100                plot.addPoint(0, i, -1.0, true);
101            }
102        }
103
104        plot.addPoint(0, 400.0, 0.0, true);
105    }
106}