Thread: Vector Addition with small numbers giving NaN

        public void addVector(mVector v) {
		double rx = v.getXComponent()+getXComponent();
		double ry = v.getYComponent()+getYComponent();
		mag = Math.sqrt((rx*rx)+(ry*ry));
		dir = Math.toDegrees(Math.atan(ry/rx));
	}
	public double getXComponent() {
		return (mag*Math.cos(Math.toRadians(dir)));
	}
	public double getYComponent() {
		return (mag*Math.sin(Math.toRadians(dir)));
	}

When adding an mVector with a mag and dir of 0 to an mVector with a mag of .735 and a dir of 90 I keep getting NaN results

public class mVector {
	public double mag;
	public double dir;
	public mVector(double mag, double dir) {
		this.mag = mag;
		this.dir = dir;
	}
 
	public void addVector(mVector v) {
		double rx = v.getXComponent()+getXComponent();
		double ry = v.getYComponent()+getYComponent();
		System.out.println("("+v.getXComponent()+", "+v.getYComponent()+")+("+getXComponent()+", "+getYComponent()+")");
		mag = Math.sqrt((rx*rx)+(ry*ry));
		dir = Math.toDegrees(Math.atan(ry/rx));
		System.out.println(0*Math.cos(Math.toRadians(0)));
	}
 
	public double getXComponent() {
		return (mag*Math.cos(Math.toRadians(dir)));
	}
	public double getYComponent() {
		return (mag*Math.sin(Math.toRadians(dir)));
	}
	public String toString() {
		return mag+"@"+dir;
	}
}

Just incase it wasn't clear, that code is in a class called mVector, and it is an instance of that class, with a mag of 0 and a dir of 0, that I call
mv.addVector(new mVector(.735,90));

I just quickly ran the code with those values and didn't get any NaN

Hah, okay, the problem was hat I was passing a 0 for magnitude of new vector...rather than .735 as predicted...uncaught loss of precision due to multiplying by a long perhaps..

Actually, that was NOT the problem. I put a println to show the value of v.mag was non-zero, and still not working, so I made a tester class, run this:

public class mVectorTester {
 
    /**
     * Creates a new instance of <code>mVectorTester</code>.
     */
    public mVectorTester() {
    }
 
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        mVector mv = new mVector(0,0);
        long delta = 10;
        double Ag = 49.0;
        double Ag2 = (Ag*delta)/1000;
        System.out.println(Ag2);
        long lastTime = System.currentTimeMillis();
        for(int i = 0;i<10;i++) {
        	delta = System.currentTimeMillis() - lastTime;
        	lastTime = System.currentTimeMillis();
        	Ag2 = (Ag*delta)/1000;
        	mv.addVector(new mVector(Ag2, 90));
 
        	System.out.println(Ag2);
        	try{
        		Thread.sleep(10);
        	} catch(InterruptedException e) {}
        }
    }
    /**
 * mVector.java
 *
 * A Vector describing either a velocity or a force
 *	mag - The magnitude of the vector in m/s
 *  dir - The direction of the vector in degrees
 * @author Ralph Landon
 * @version 1.00 2010/10/28
 */
private static class mVector {
	public double mag;
	public double dir;
	public mVector(double mag, double dir) {
		this.mag = mag;
		this.dir = dir;
	}
 
	public void addVector(mVector v) {
		double rx = v.getXComponent()+getXComponent();
		double ry = v.getYComponent()+getYComponent();
		System.out.println(v.mag);
		System.out.println("("+v.getXComponent()+", "+v.getYComponent()+")+("+getXComponent()+", "+getYComponent()+")");
		mag = Math.sqrt((rx*rx)+(ry*ry));
		dir = Math.toDegrees(Math.atan(ry/rx));
		System.out.println(0*Math.cos(Math.toRadians(0)));
	}
 
	public double getXComponent() {
		return (mag*Math.cos(Math.toRadians(dir)));
	}
	public double getYComponent() {
		return (mag*Math.sin(Math.toRadians(dir)));
	}
	public String toString() {
		return mag+"@"+dir;
	}
}
}