anchor.diff:  (defparameter *height* 400)
   (defparameter *location* nil)
   (defparameter *velocity* nil)
  +(defparameter *acceleration* nil)
   (defparameter *mouse* nil)
   (defparameter *center* nil)
   
  
positive.code: (defparameter *y* 0)
  (defparameter *xspeed* 0)
  (defparameter *yspeed* 0)
  
  
  (defclass pvector ()
  
negative.code:   (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)))))
  