anchor.diff:  ;; Unit conversions, etc.
   ;;
   ;;  1 knot = 1.852000 km/hr*
  -;;  1 knot = 185200/109728 ft/sec* =1.687810 ft/sec
  +;;  1 knot = 185200/109728 ft/sec* = 1.687810 ft/sec
   ;;  1 knot = 1852000/1609344 mph* = 1.150779 mph
   ;;  1 mph  = 0.868976 knot
   ;;  1 mph  = 1.609344 km/hr*
  
positive.code: that type."
    (let ((new-obj nil))
      (if (null point-type)
  	(setf new-obj (make-instance (second (assoc 'type point-data))))
        (setf new-obj (make-instance point-type)))
      (point-deserialize-method new-obj point-data)
      new-obj
      )
  
negative.code:     (setf lat (asin (+ (* (sin lat1) (cos d)) (* (cos lat1) (sin d) (cos az)))))
      (setf dlon (atan (* (sin az) (sin d) (cos lat1)) (- (cos d) (* (sin lat1) (sin lat)))))
      (setf lon (- 0 (- (my-mod (+ (- lon1 dlon) pi) (* 2 pi)) pi)))
      (make-instance '2d-point
  		   :creation-source point-generated
  		   :lat (rad-to-deg lat)
  		   :lon (rad-to-deg lon))))
  
  (defun serialize-points-to-file (points filename)
    "Write a list of points to a file."
    (with-open-file
        (file-handle filename
  		   :direction :output
  		   :if-does-not-exist :create
  		   :if-exists :supersede)
      (mapcar
       #'(lambda (n)
  	 (format file-handle "~A~%" (point-serialize n)))
       points)))
  
  (defun deserialize-points-from-file (filename)
    "Read in a list of points from a file."
  