A naive implementation of row-major double precision floating point general matrix multiplication (DGEMM) in Common Lisp.

dgemm_row.lisp

;; row major matrix multiplication
(defun row_major_mm (a b c)
  (flet (
	 (col (mat i) (mapcar #'(lambda (row) (elt row i)) mat))
	 (row (mat i) (elt mat i))
        )

    	(loop for k from 0 below (length (row a 0))
	  do (loop for i from 0 below (length a)
			do (let ((temp (elt (elt a i) k)))
			        (loop for j from 0 below (length a)
				      do (setf (nth j (nth i c))
					       (+ (elt (elt c i) j)
						  (* temp (elt (elt b k) j))
					       )
					 )
				)
			   )
	     )
	)
  )
)

;; create a double floating point random matrix
(defun get_random_matrix (N)
	(loop for i from 0 below N
	      collect (loop for j from 0 below N
			      collect (random 1d0)
			)
	)
)

(loop for num_runs from 0 below 100
	do (loop for N from 10 below 100
	      do (let ((a (get_random_matrix N)) (b (get_random_matrix N)) (c (get_random_matrix N)))

			;; warm-up
			(row_major_mm a b c)

			;; run enough number of times to calculate FLOPS
			(time (loop for i from 0 below 10
			      do (row_major_mm a b c)))
		 )
	)
)