this.set = function(v)
      {
        this.x = v.getX(); 
        this.y = v.getY(); 
      }
      this.add = function(v)
      {
        this.x += v.getX(); 
        this.y += v.getY(); 
      }
      this.sub = function(v)
      {
        this.x -= v.getX(); 
        this.y -= v.getY(); 
      }
      this.dotProd = function(v)
      {
        return this.x * v.getX() + this.y * v.getY(); 
      }
      this.length = function()
      {
        return Math.sqrt(this.x * this.x + this.y * this.y); 
      }
      this.scale = function(scaleFactor)
      {
        this.x *= scaleFactor; 
        this.y *= scaleFactor; 
      }
      this.toString = function()
      {
        return " X: " + this.x + " Y: " + this.y; 
      }
    }