ThreeBodyAPL.java

package jat.examples.ThreeBodyExample;

import java.util.ArrayList;

import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;
import org.apache.commons.math3.ode.FirstOrderDifferentialEquations;
import org.apache.commons.math3.ode.sampling.StepHandler;
import org.apache.commons.math3.ode.sampling.StepInterpolator;

import jat.coreNOSA.algorithm.integrators.Printable;
import jat.coreNOSA.cm.Constants;
import jat.coreNOSA.cm.ThreeBody;
import jat.coreNOSA.math.MatrixVector.data.VectorN;

public class ThreeBodyAPL extends ThreeBody implements FirstOrderDifferentialEquations{
	public ArrayList<Double> time = new ArrayList<Double>();
	public ArrayList<Double> xsol = new ArrayList<Double>();
	public ArrayList<Double> ysol = new ArrayList<Double>();
	public ArrayList<Double> zsol = new ArrayList<Double>();
	
	/*
	 * Why we created the ThreeBodyAPL:
	 * The APL is responsible for computing the derivatives used in the ThreeBodyExample and interpolating data
	 * APL stands for Applied Physics Laboratory
	 */
	
	/*
	 * What we used from existing code
	 * The information that this class uses from the ThreeBody class are calculations for:
	 * Masses, center of mass and energy. 
	 * This is usefull for us because all of this is necessary for our modification
	 */

	public ThreeBodyAPL(double G, double m1, double m2, double m3) {
		super(G, m1, m2, m3);
	}
	
	@Override
	public void computeDerivatives(double t, double[] y, double[] yDot) {
		// returns the derivatives of the ThreeBody problem
		yDot = this.derivs(t, y);
	}
	
	@Override
	public int getDimension() {
		// returns a dimension of 6
		return 18;
	}
	public double[] randv() {
		// returns the position and velocity of the three objects
		// vector r1 is x[0], x[1], x[2]
		// vector v1 is x[3], x[4], x[5]
		// vector r2 is x[6], x[7], x[8]
		// vector v2 is x[9], x[10], x[11]
		// vector r3 is x[12], x[13], x[14]
		// vector v3 is x[15], x[16], x[17]
		double[] randv = new double[18];
		randv[0] = 2.0;
		randv[1] = 6.0;
		randv[2] = 7.0;
		randv[3] = 4.0;
		randv[4] = 8.0;
		randv[5] = 7.0;
		randv[6] = 5.0;
		randv[7] = 8.0;
		randv[8] = 3.0;
		randv[9] = 6.0;
		randv[10] = 8.0;
		randv[11] = 9.0;
		randv[12] = 0.0;
		randv[13] = 7.0;
		randv[14] = 4.0;
		randv[15] = 5.0;
		randv[16] = 7.0;
		randv[17] = 8.0;
		return randv;
	}

	public StepHandler stepHandler = new StepHandler() {
		public void init(double t0, double[] y0, double t) {
		}

		public void handleStep(StepInterpolator interpolator, boolean isLast) {
			double t = interpolator.getCurrentTime();
			double[] y = interpolator.getInterpolatedState();
			System.out.println(t + " " + y[0] + " " + y[1]+ " " + y[2]);
			time.add(t);
			xsol.add(y[0]);
			ysol.add(y[1]);
			zsol.add(y[2]);
		}
	};
	
}