Point

luis

///**
// * Created by dcrystalj on 28.4.2014.
// */
public class Point {
    int x,y;

    public int dot(Point p) {
        return this.x * p.x + this.y * p.y;
    }

    public double length() {
        return Math.sqrt(x*x + y*y);
    }

    public double distance(Point p) {
        return this.minus(p).length();
    }

    public double angle (Point p, Point prev) {
        Point start = prev.minus(this).negate();
        Point end = p.minus(this);
        double length = start.length() * end.length();
        if (length == 0)
            return 0;

        return Math.acos(
                Math.round( ((double) start.dot(end) / length) *100 )/100.0
               ); // * 57.29577951308232; //multiply by 180/Math.PI == 57.29577951308232 for easier testing;
    }

    private Point negate () {
        return new Point(this.x * -1, this.y * -1);
    }

    private Point minus (Point point) {
        return new Point(this.x - point.x, this.y-point.y);
    }

    /**
     * Constructor
     *
     * @param x
     * @param y
     */
    public Point(int x, int y){
        this.x = x;
        this.y = y;
    }

    public String toString() {
        return  "x: "+x + " y: "+y;
    }
}