anchor.diff:  (defmeth2 * ((a array) (b array))
     (destructuring-bind (m p) (array-dimensions a)
       (destructuring-bind (p n) (array-dimensions b)
  -      (let ((c (make-array (list m n))))
  +      (let ((c (make-array (list m n) :initial-element 0)))
   	(dotimes (i m)
   	  (dotimes (j n)
   	    (setf (aref c i j) 
  
positive.code: (defun copya (a)
    "Copy 2D array"
    (let* ((dim (array-dimensions a))
  	 (acpy (make-array dim)))
      (dotimes (i (reduce #'* dim))
        (setf (row-major-aref acpy i) (row-major-aref a i)))
      acpy))
  
negative.code: (defmeth2 + ((a array) (b array))
    (assert (equal (array-dimensions a) (array-dimensions b)))
    (destructuring-bind (m n) (array-dimensions a)
      (let ((c (make-array (list m n) :initial-element 0)))
        (dotimes (i (* m n))
  	(setf (row-major-aref c i) (+ (row-major-aref a i) (row-major-aref b i))))
        c)))
    
  (defmeth2 * ((a array) (s number))
    (destructuring-bind (m n) (array-dimensions a)
      (let ((b (make-array (list m n) :initial-element 0)))
        (dotimes (i (* m n))
  	(setf (row-major-aref b i) (* (row-major-aref a i) s)))
        b)))
  