anchor.diff:            for i = 1 then (1+ i)
             for rate = (compute-ode-expression (nth (1- i) (numerica-model-ode-rates nm)) nm)
             do  (with-print-context t 
  +                (princ #\.)
                   ;; write comment
                   (if (numerica-model-ode-comments-p nm)
                       (b-format file "~%~4T# ~A = ~A " v rate))
  
positive.code:     (let ((end (file-position file)))
        (file-position file klen-pos)
        (princ (numerica-model-kvar-count nm) file)
        (file-position file end))))
  
  
  (defun compute-display-var-indicies (nm)
  
negative.code:   (write-model-block nm file)
    (write-simulation-block nm file)
    
    (format t "~&The following file has been writted: ~A~%"
            (enough-namestring file)))
  
  ;;;
  ;;; helper functions which write numerica code to a stream:
  