import java.awt.*; import java.awt.event.*; import java.applet.Applet; import java.awt.image.*; /** * Class Duffing_Orbit - oscilloscope-like display of the duffing-oscillator's orbit y(t) * created with BlueJ * * @author (Martin Lieberherr) */ public class Duffing_Orbit extends Applet implements ActionListener, Runnable { // instance variables and attributes (all private) int nx = 800; // number of pixels in x-direction for picture int ny = 400; // number of pixels in y-direction for picture // d2y/dt^2 + delta*dy/dt + alpha*y + beta*y^3 = gamma*cos(omega*t) double delta = 0.1; // coefficient of damping (prop. velocity) double alpha=1.0; // coefficient of linear force-term double beta=0.0; // coefficient of cubic force term double gamma = 0.1; // coefficient of forcing double omega = 0.333; // angular frequency of forcing double yMax = 1.0; // vertical window display -yMax..+yMax double tMin = 0.0; // horizontal window display tMin..tMax double tMax = 100; // horizontal window display tMin..tMax double yStart = 0; // start position for orbit y(t) int stepsPerCycle = 1000; // steps per cycle for Runge-Kutta integrator boolean mouseFlag = false; // true if mouse is clicked in graphical display int mouse_i = 1; // position relative to graphical display where clicking occurred Label titleLabel; // displays "Orbit y(t) of forced Duffing-oscillator" Label authorLabel; // displays author-name and date Label alphaLabel; // displays "alpha:" TextField alphaField; // display/input coefficient alpha. Label betaLabel; // displays "beta:" TextField betaField; // display/input coefficient beta Label gammaLabel; // displays "gamma:" TextField gammaField; // display/input coefficient gamma Label deltaLabel; // displays "delta:" TextField deltaField; // display/input coefficient delta Label omegaLabel; // displays "omega:" TextField omegaField; // diplay/input omega Label yNullLabel; // displays "y=0" TextField yMaxField; // display/input yMax Label yMinLabel; // displays yMin (= - yMax) Label timeLabel; // displays "time" TextField tMinField; // dispay/input tMin TextField tMaxField; // display/input tMax Label stepsLabel; // display "steps:" TextField stepsField; // display/input stepsPerCycle Label yStartLabel; // displays "y(0):" TextField yStartField; // display/input y(0) Thread thread; // loop to numerically integrate the movement // buffered image for display of positions BufferedImage BuffImage1 = new BufferedImage(nx, ny, BufferedImage.TYPE_INT_RGB); Graphics g1 = BuffImage1.createGraphics(); /** * Called by the browser or applet viewer to inform this Applet that it * has been loaded into the system. It is always called before the first * time that the start method is called. */ public void init() { setLayout(null); // for "hard" layout in pixels int xText = 10; // position of next element on window int yText = 10; // position of next element on window yMaxField = new TextField(""+yMax); yMaxField.setBounds(xText, yText, 80, 20); add(yMaxField); yMaxField.addActionListener(this); yText = ny/2; yNullLabel = new Label("y = 0"); yNullLabel.setBounds(xText, yText, 40, 20); add(yNullLabel); yText = ny-10; yMinLabel = new Label("-"+yMax); yMinLabel.setBounds(xText,yText,80,20); add(yMinLabel); xText = 100; yText = 20+ny; tMinField = new TextField(""+tMin); tMinField.setBounds(xText, yText, 100, 20); add(tMinField); tMinField.addActionListener(this); xText = xText+10+nx/2-20; timeLabel = new Label("time"); timeLabel.setBounds(xText, yText, 40, 20); add(timeLabel); xText = 100+nx-100; tMaxField = new TextField(""+tMax); tMaxField.setBounds(xText, yText, 100, 20); add(tMaxField); tMaxField.addActionListener(this); xText = 100; yText = yText + 40; titleLabel = new Label("Orbit of forced Duffing-oscillator"); titleLabel.setBounds(xText, yText, 300, 20);// setBounds(x_left, y_top, width, height) for display add(titleLabel); //added to ContentPane to the right of picture xText = 100+nx-300; authorLabel = new Label("Martin Lieberherr, September 9th, 2011"); authorLabel.setBounds(xText, yText, 300, 20); add(authorLabel); xText = 100; yText = yText+30; alphaLabel = new Label("alpha:"); alphaLabel.setBounds(xText, yText, 40, 20); // setBounds(x_left, y_top, width, height) for display add(alphaLabel); //added to ContentPane to the right of picture xText=xText+10+40; alphaField = new TextField(""+alpha); alphaField.setBounds(xText, yText, 150, 20); add(alphaField); alphaField.addActionListener(this); // ActionListener is called if "enter" is pressed in TextField xText = xText+200; betaLabel = new Label("beta:"); betaLabel.setBounds(xText, yText, 40, 20); add(betaLabel); xText = xText+10+40; betaField = new TextField(""+beta); betaField.setBounds(xText, yText, 150, 20); add(betaField); betaField.addActionListener(this); xText = xText+200; gammaLabel = new Label("gamma:"); gammaLabel.setBounds(xText, yText, 55, 20); add(gammaLabel); xText = xText+10+60; gammaField = new TextField(""+gamma); gammaField.setBounds(xText, yText, 150, 20); add(gammaField); gammaField.addActionListener(this); xText = 100; yText = yText+30; deltaLabel = new Label("delta:"); deltaLabel.setBounds(xText, yText, 40, 20); add(deltaLabel); xText = xText+10+40; deltaField = new TextField(""+delta); deltaField.setBounds(xText, yText, 150, 20); add(deltaField); deltaField.addActionListener(this); xText = xText+190; omegaLabel = new Label("omega:"); omegaLabel.setBounds(xText, yText, 50, 20); add(omegaLabel); xText = xText+10+50; omegaField = new TextField(""+omega); omegaField.setBounds(xText, yText, 150, 20); add(omegaField); omegaField.addActionListener(this); xText = xText+ 200; yStartLabel = new Label("y(0):"); yStartLabel.setBounds(xText, yText, 60, 20); add(yStartLabel); xText = xText+10+60; yStartField = new TextField(""+yStart); yStartField.setBounds(xText, yText, 150, 20); add(yStartField); yStartField.addActionListener(this); xText = 100; yText = yText+30; stepsLabel = new Label("steps:"); stepsLabel.setBounds(xText, yText, 40, 20); add(stepsLabel); xText = xText+10+40; stepsField = new TextField(""+stepsPerCycle); stepsField.setBounds(xText, yText, 150, 20); add(stepsField); stepsField.addActionListener(this); thread = new Thread(this); // thread is a new thread of this applet thread.start(); // start the thread } // end init () public void destroy() { thread = null; // set thread to zero if applet is stopped } /** update()-method for applet * (overridden to avoid flicker) * @param g the Grapics object for this applet */ public void update( Graphics g ) { //display buffered image with oscilloscope-trace g.drawImage( BuffImage1, 100, 10, null); } // end update() /** * Paint method for applet. * * @param g the Graphics object for this applet */ public void paint(Graphics g) { update( g ); } // end paint() /** * ActionListener Interface method. * Called when action events occur with registered components that * can fire action events. * @param ae the ActionEvent object created by the event */ public void actionPerformed(ActionEvent evt) { // if a value for alpha is entered if (evt.getSource() == alphaField) { try { alpha = Double.parseDouble(alphaField.getText()); alphaField.setText(""+alpha); } catch (NumberFormatException e) { alphaField.setText(""+alpha); // System.exit(0); } } // if a value for beta is entered if (evt.getSource() == betaField) { try { beta = Double.parseDouble(betaField.getText()); betaField.setText(""+beta); } catch (NumberFormatException e) { betaField.setText(""+beta); // System.exit(0); } } // if a value for gamma is entered if (evt.getSource() == gammaField) { try { gamma = Double.parseDouble(gammaField.getText()); gammaField.setText(""+gamma); } catch (NumberFormatException e) { gammaField.setText(""+gamma); // System.exit(0); } } // if a value for delta is entered if (evt.getSource() == deltaField) { try { delta = Double.parseDouble(deltaField.getText()); deltaField.setText(""+delta); } catch (NumberFormatException e) { deltaField.setText(""+delta); // System.exit(0); } } // if a value for omega is entered if (evt.getSource() == omegaField) { try { omega = Double.parseDouble(omegaField.getText()); if (omega <= 0.0) {omega = 0.333;} omegaField.setText(""+omega); } catch (NumberFormatException e) { omegaField.setText(""+omega); // System.exit(0); } } // if a value for yStart is entered if (evt.getSource() == yStartField) { try { yStart = Double.parseDouble(yStartField.getText()); yStartField.setText(""+yStart); } catch (NumberFormatException e) { yStartField.setText(""+yStart); // System.exit(0); } } // if a value for yMax is entered if (evt.getSource() == yMaxField) { try { yMax = Double.parseDouble(yMaxField.getText()); if (yMax <=0) {yMax=1.0;} yMaxField.setText(""+yMax); yMinLabel.setText("-"+yMax); } catch (NumberFormatException e) { yMaxField.setText(""+yMax); // System.exit(0); } } // if a value for tMin is entered if (evt.getSource() == tMinField) { try { tMin = Double.parseDouble(tMinField.getText()); if (tMin < 0.0) {tMin = 0.0;} if (tMin >= tMax) {tMax = tMin + 1.0; tMaxField.setText(""+tMax);} tMinField.setText(""+tMin); } catch (NumberFormatException e) { tMinField.setText(""+tMin); // System.exit(0); } } // if a value for tMax is entered if (evt.getSource() == tMaxField) { try { tMax = Double.parseDouble(tMaxField.getText()); if (tMax <= tMin) {tMax = tMin+1.0;} tMaxField.setText(""+tMax); } catch (NumberFormatException e) { tMaxField.setText(""+tMax); // System.exit(0); } } // if a value for stepsPerCycle is entered if (evt.getSource() == stepsField) { try { stepsPerCycle = (int) Math.round(Double.parseDouble(stepsField.getText())); if (stepsPerCycle < 10) {stepsPerCycle=10;} stepsField.setText(""+stepsPerCycle); } catch (NumberFormatException e) { stepsField.setText(""+stepsPerCycle); // System.exit(0); } } thread = new Thread(this); // thread is a new thread of this applet thread.start(); // start the thread } // end actionPerformed() public void run(){ double t, y, v; // time, position and velocity in the current state double dt; // time step for numerical integration int k; double t00, y0, v0, t1, dy1, dv1, t2, dy2, dv2, t3, dy3, dv3, dy4, dv4; // variables for Runge-Kutta integrator try{ t = 0.0; y = yStart; v = 0.0; dt = 2.0*Math.PI/omega/stepsPerCycle; g1.setColor(Color.black); g1.fillRect(0, 0, nx, ny); g1.setColor(new Color( 0 , 255, 0) ); // orbit for 0 <= t <= tMin is not displayd while (t