3.59
cosine と sine は思い付かなかった。頭いーな。
http://www.parsprototo.org/StoppingTime/?p=7
;;; a (define (integrate-series a) (define (merge-series a s) (cons-stream (/ (stream-car a) (stream-car s)) (merge-series (stream-cdr a) (stream-cdr s)))) (merge-series a (integers-starting-from 1))) ;;; b (define exp-series (cons-stream 1 (integrate-series exp-series))) (define cosine-series (cons-stream 1 (integrate-series (stream-map (lambda (x) (- 0 x)) sine-series)))) (define sine-series (cons-stream 0 (integrate-series cosine-series)))