anchor.diff:              :initform nil
               :documentation "Cached inverse transformation.") ))
   
  -
  -#+:DEBUG
  -(defmethod initialize-instance :after ((self standard-transformation) args)
  -  (declare (ignorable self args)) )
  -
   (defmethod print-object ((self standard-transformation) sink)
  -  ;; printer
  -  (apply #'format sink "#<~S ~S ~S ~S ~S ~S ~S>"
  -         (type-of self)
  -         (multiple-value-list (get-transformation self))))
  +  (print-unreadable-object (self sink :identity nil :type t)
  +    (apply #'format sink "~S ~S ~S ~S ~S ~S"
  +           (multiple-value-list (get-transformation self)))))
   
   (defun make-transformation (mxx mxy myx myy tx ty)
     ;; Make a transformation, which will map a point (x,y) into
  
positive.code: 		     (transformation-error-rect self)
  		     (transformation-error-transformation self)))))
  
  (defmethod transformation-equal ((transformation1 standard-transformation) (transformation2 standard-transformation))
    (every #'coordinate=
           (multiple-value-list (get-transformation transformation1))
           (multiple-value-list (get-transformation transformation2))))
  
negative.code: ;;;;  Transformations
  ;;;;
  
  (define-protocol-class transformation ())
  
  (defclass standard-transformation (transformation)
    ((mxx :type coordinate)
  