anchor.diff:    (setf (x vec) (/ (x vec) n))
     (setf (y vec) (/ (y vec) n)))
   
  -
   (defun mag-vectors (vec)
     (sqrt (+ (* (x vec) (x vec))
   	   (* (y vec) (y vec)))))
  
positive.code: (defparameter *height* 400)
  (defparameter *location* nil)
  (defparameter *velocity* nil)
  (defparameter *mouse* nil)
  (defparameter *center* nil)
  
  
negative.code: (defparameter *y* 0)
  (defparameter *xspeed* 0)
  (defparameter *yspeed* 0)
  (defparameter *topspeed* 0)
  
  
  (defclass pvector ()
  