creation of ThreeBodyAPL and ThreeBodyExample main class. Most of the

ThreeBodyExample class is the same as the TwoBodyExample class, and will
be further elaborated later on after a model of the Three Body
Gravitational problem is defined.

src/jat/examples/ThreeBodyExample/ThreeBodyAPL.java

@@ -0,0 +1,25 @@
+package jat.examples.ThreeBodyExample;
+
+import org.apache.commons.math3.ode.FirstOrderDifferentialEquations;
+
+import jat.coreNOSA.cm.ThreeBody;
+
+public class ThreeBodyAPL extends ThreeBody implements FirstOrderDifferentialEquations{
+
+	public ThreeBodyAPL(double G, double m1, double m2, double m3) {
+		super(G, m1, m2, m3);
+	}
+
+	@Override
+	public void computeDerivatives(double arg0, double[] arg1, double[] arg2) {
+		// TODO Auto-generated method stub
+
+	}
+
+	@Override
+	public int getDimension() {
+		// TODO Auto-generated method stub
+		return 6;
+	}
+
+}

src/jat/examples/ThreeBodyExample/ThreeBodyExample.java

@@ -0,0 +1,95 @@
+package jat.examples.ThreeBodyExample;
+
+import jat.core.cm.TwoBodyAPL;
+import jat.core.plot.plot.FrameView;
+import jat.core.plot.plot.Plot2DPanel;
+import jat.core.plot.plot.PlotPanel;
+import jat.core.plot.plot.plots.ScatterPlot;
+import jat.examples.TwoBodyExample.TwoBodyExample;
+
+import java.awt.Color;
+import java.text.DecimalFormat;
+
+import javax.swing.JFrame;
+
+import org.apache.commons.lang3.ArrayUtils;
+import org.apache.commons.math3.linear.ArrayRealVector;
+import org.apache.commons.math3.linear.RealVectorFormat;
+import org.apache.commons.math3.ode.FirstOrderIntegrator;
+import org.apache.commons.math3.ode.nonstiff.DormandPrince853Integrator;
+
+public class ThreeBodyExample {
+	public ThreeBodyExample() {
+	}
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		ThreeBodyExample x = new ThreeBodyExample();
+
+		// create a TwoBody orbit using orbit elements
+		ThreeBodyAPL sat = new ThreeBodyAPL(10, 0.3, 1.0, 2.0);
+
+		double[] y = sat.randv();
+
+		ArrayRealVector v = new ArrayRealVector(y);
+
+		DecimalFormat df2 = new DecimalFormat("#,###,###,##0.00");
+		RealVectorFormat format = new RealVectorFormat(df2);
+		System.out.println(format.format(v));
+
+		// find out the period of the orbit
+		double period = sat.period();
+
+		// set the final time = one orbit period
+		double tf = period;
+
+		// set the initial time to zero
+		double t0 = 0.0;
+
+		// propagate the orbit
+		FirstOrderIntegrator dp853 = new DormandPrince853Integrator(1.0e-8, 100.0, 1.0e-10, 1.0e-10);
+		dp853.addStepHandler(sat.stepHandler);
+		// double[] y = new double[] { 7000.0, 0, 0, .0, 8, 0 }; // initial
+		// state
+
+		dp853.integrate(sat, 0.0, y, 8000, y); // now y contains final state at
+												// tf
+
+		Double[] objArray = sat.time.toArray(new Double[sat.time.size()]);
+		double[] timeArray = ArrayUtils.toPrimitive(objArray);
+		double[] xsolArray = ArrayUtils.toPrimitive(sat.xsol.toArray(new Double[sat.time.size()]));
+		double[] ysolArray = ArrayUtils.toPrimitive(sat.ysol.toArray(new Double[sat.time.size()]));
+
+		double[][] XY = new double[timeArray.length][2];
+
+		// int a=0;
+		// System.arraycopy(timeArray,0,XY[a],0,timeArray.length);
+		// System.arraycopy(ysolArray,0,XY[1],0,ysolArray.length);
+
+		for (int i = 0; i < timeArray.length; i++) {
+			XY[i][0] = xsolArray[i];
+			XY[i][1] = ysolArray[i];
+		}
+
+		Plot2DPanel p = new Plot2DPanel();
+
+		// Plot2DPanel p = new Plot2DPanel(min, max, axesScales, axesLabels);
+
+		ScatterPlot s = new ScatterPlot("orbit", Color.RED, XY);
+		// LinePlot l = new LinePlot("sin", Color.RED, XY);
+		// l.closed_curve = false;
+		// l.draw_dot = true;
+		p.addPlot(s);
+		p.setLegendOrientation(PlotPanel.SOUTH);
+		double plotSize = 10000.;
+		double[] min = { -plotSize, -plotSize };
+		double[] max = { plotSize, plotSize };
+		p.setFixedBounds(min, max);
+
+		new FrameView(p).setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+
+		System.out.println("end");
+
+	}
+
+}