(defmacro with-matrix-elements (matrix &body body)
  `(let ((rows (number-of-rows ,matrix))
     (cols (number-of-cols ,matrix)))
     (declare
      (type fixnum rows cols)
      (optimize (debug 0) (safety 0) (speed 3)))
     (loop for i fixnum from 0 below rows
       do
         (loop for j from 0 below cols
          do
           ,@body))))


(defmethod self-print ((matrix r-matrix-sfp))
  (print-object matrix t)
  (format t "~%Matrix elements:~%")
  (with-matrix-elements matrix
    (format t "~TA(~a,~a)=~,4e~%" i j (mref matrix i j))))