SICP 問題 3.76
前回のデータと比べて平均化する.
(define (smooth stream) (cons-stream (average (car stream) 0) (stream-map average (stream-cdr stream) stream))) (define (make-zero-crossings sense-data) (let ((smooth-data (smooth sense-data))) (stream-map sign-change-detector smooth-data (cons-stream 0 smooth-data))))