I need to create a graph of the kinetic, potential, and total energy as a function of time for an n-body system using Java. The code I have so far is below:

NBodyObject.java

import java.awt.*; import org.opensourcephysics.display.*;

public class NBodyObject implements Drawable { double cof,dt,t,E,K,P,T; int nspeed,nbody; private double dx,dy,b,dr,dr2; final static int arraysize = 100;

Trail trail = new Trail(); double x[]=new double[arraysize]; double y[]=new double[arraysize]; double vx[]=new double[arraysize]; double vy[]=new double[arraysize]; double ax[]=new double[arraysize]; double ay[]=new double[arraysize]; double r[] =new double[arraysize]; double r2[]=new double[arraysize]; double KE[]=new double[arraysize]; double PE[]=new double[arraysize]; double TE[]=new double[arraysize];

public NBodyObject(){System.out.println("A new NBody object is created."); } //-------------object properties // public void energy(){ // E=0.5*(vx*vx+vy*vy)-1./Math.sqrt(x*x+y*y); // } public void accel(){ for(int i = 0;i

} public void nbaccel(){ // for(int i = 0;i

accel(); for(int i = 0;i

} //------------------object motion public void positionstep(double cof){ for(int i = 0;i

public void draw(DrawingPanel panel, Graphics g) { int irad=5; int xpix = panel.xToPix(0.0)-irad; int ypix = panel.yToPix(0.0)-irad; //sun at the origin g.setColor(Color.BLUE); g.fillOval(xpix, ypix, 2*irad, 2*irad);

irad=5; //smaller moving planet for(int i = 0;i

for(int i = 0;i

}

NBodyApp.java

import org.opensourcephysics.controls.*; import org.opensourcephysics.display.*; import org.opensourcephysics.frames.*;

/** * PlanetApp models an orbiting planet. * * This program demonstrates: * how to use the Simulation control to run and single step a time dependent model. * * @author Wolfgang Christian, Jan Tobochnik, Harvey Gould * @version 1.0 */ public class NBodyApp extends AbstractSimulation { PlotFrame frame = new PlotFrame("x", "y", "N-Body Orbits");

NBodyObject planet = new NBodyObject();

/** * Constructs the PlanetApp. */ public NBodyApp() { frame.setSize(600,600); frame.addDrawable(planet); // frame.setPreferredMinMax(-1.2, 1.2, -1.2, 1.2); frame.setPreferredMinMax(-10., 25., -30., 30.); frame.setSquareAspect(true); }

/** * Steps the time. */ public void doStep() { // planet.trail.clear(); for(int i = 0;i

/** * Resets animation to a predefined state. */ public void reset() { // control.setValue("x", 10.0); // control.setValue("vx", 0.00); // control.setValue("y", 0.00); // control.setValue("vy", 0.10); control.setValue("nbody", 3); control.setValue("dt", 0.01); control.setValue("nspeed", 10); initialize(); }

/** * Starts the Java application. * @param args command line parameters */ public static void main(String[] args) { SimulationControl.createApp(new NBodyApp()); } }