anchor.diff:  
   
   (defun compute-array-vector* (m)
  -  ;; FIXME: Move this DEFUN to the MCi CLtL 'utils' system
     (declare (type array m)
              (values (simple-array t (*))))
     (let ((dims (array-dimensions m)))
  
positive.code: (defun column (m j)
    (declare (type array-dimension-designator j)
             (type (array t (* *)) m)
             (values (array t (1 *)) m))
    (let* ((n-rows (array-dimension m 0))
           (reslt (make-array (list n-rows 1)
                              :element-type (array-element-type m))))
      (dotimes (n n-rows reslt)
        (setf (aref reslt n 0) 
              (aref m n j))
      )))
  
  ;; (column #2A((1 2 3 4) (4 3 2 1)) 0)
  ;; => #2A((1) (4))
  
negative.code: 
  ;; (gaussian-reduction #2A((1 1 2 0 1) (2 -1 0 1 -2) (2 -1 -1 -2 4) (2 -2 2 -1 0)))
  
  