X-Git-Url: https://git.rkrishnan.org/?a=blobdiff_plain;f=src%2Fsicp%2Fex2_37.rkt;h=a0c71f998b4361f4b4ab486ea164f76ce4c3cc0b;hb=ccf01641182e264e51decf6c62650b1b6ad809c8;hp=841e6c27c68175a09da8a8852986a249c5eab7ff;hpb=95b2ccf229800dc12a8cb9830fc8986509211ff6;p=sicp.git diff --git a/src/sicp/ex2_37.rkt b/src/sicp/ex2_37.rkt index 841e6c2..a0c71f9 100644 --- a/src/sicp/ex2_37.rkt +++ b/src/sicp/ex2_37.rkt @@ -10,13 +10,14 @@ (define (matrix-*-vector m v) (map (lambda (r) (dot-product r v)) m)) -;; (matrix-*-vector '((1 2 3 4) (4 5 6 6) (6 7 8 9)) '(1 2 3 4)) +(matrix-*-vector '((1 2 3 4) (4 5 6 6) (6 7 8 9)) '(1 2 3 4)) (define (transpose m) (accumulate-n cons '() m)) ;; (transpose '((1 2 3) (4 5 6) (7 8 9))) + (define (matrix-*-matrix m n) (let ([cols (transpose n)]) (map (lambda (v) (matrix-*-vector cols v)) m)))