anchor.diff:    (funcall
      fun
      (+ tm (* h (aref c i)))
  -   (+ (* (aref k i) h) x)))
  -(defun kall (fun tm h x s c a)
  +   (+ (* (aref k i) h) x)
  +   param))
  +(defun kall (fun tm h x s c a param)
     "Calculate vector of K values"
     (let ((k (make-array 7)))
  -    (setf (aref k 0) (funcall fun tm x))
  +    (setf (aref k 0) (funcall fun tm x param))
       (loop for i from 1 below s
          do (setf (aref k i)
  -		(ki fun tm i h x k c a)))
  +		(ki fun tm i h x k c a param)))
       k))
   (defun xnext (x h k b)
     "Calculate next state"
  
positive.code: (in-package :bld-ode)
  
  ;; Stepping functions
  (defun ki (fun tm i h x k c a)
    "Calculate intermediate k value"
    (setf (aref k i) (* (aref k 0) (aref a i 0)))
    (loop for j from 1 below i
  
negative.code:      with h = h0 ; stepsize
       with x = x0 ; state
       until (or (>= tm tf) (< h hmin)) ; end: final time, h too small
       for k = (kall fun tm h x s c a param) ; k values used in state estimates
       for xl = (xnext x h k bl) ; lower order estimate
       for xh = (xnext x h k bh) ; higher order estimate
       for err = (norminfx (- xh xl)) ; error estimate
  