anchor.diff:  			       (format stream " ~a ~a" k v))) h)
     (format stream ">"))
   
  -;; Macro to define state arithmethic on a custom class
  +;;; Macro to define state arithmethic on a custom class
   (defmacro defstatearithmetic (class slots &key (initargs (mapcar #'make-keyword slots)))
     "Defines state arithmetic for specified class and slots.
   Assumes state arithmetic already defined for slot types, including NORMINFX.
  
positive.code: 
  (in-package :bld-ode)
  
  ;; Infinity norm of an ODE state
  (defgeneric norminfx (x)
    (:documentation "Infinity norm of a state"))
  
  ;; Infinity norm of a number
  (defmethod norminfx ((x number))
    (abs x))
  
  ;; Vector state arithmetic
  
  (defmeth2 + ((a vector) (b vector)) 
    (map 'vector #'+ a b))
  
negative.code: (defmethod norminfx ((x vector))
    (reduce #'max (map 'vector #'norminfx x)))
  
  ;;; Hash table state arithmetic
  
  (defmeth2 + ((a hash-table) (b hash-table))
    (let ((result (make-hash-table)))
  