SICP 問題 3.65
(define (ln2-summands n) (cons-stream (/ 1.0 n) (stream-map - (ln2-summands (+ n 1))))) (define ln2-stream (partial-sums (ln2-summands 1)))
gosh> (stream-head ln2-stream 20) 1.0 0.5 0.8333333333333333 0.5833333333333333 0.7833333333333332 0.6166666666666666 0.7595238095238095 0.6345238095238095 0.7456349206349207 0.6456349206349207 0.7365440115440116 0.6532106782106782 0.7301337551337552 0.6587051837051838 0.7253718503718505 0.6628718503718505 0.7216953797836152 0.6661398242280596 0.718771403175428 0.6687714031754279 done gosh> (stream-head (euler-transform ln2-stream) 20) 0.7 0.6904761904761905 0.6944444444444444 0.6924242424242424 0.6935897435897436 0.6928571428571428 0.6933473389355742 0.6930033416875522 0.6932539682539683 0.6930657506744464 0.6932106782106783 0.6930967180967181 0.6931879423258734 0.6931137858557215 0.6931748806748808 0.6931239512121866 0.6931668512550866 0.6931303775344023 0.693161647077867 0.6931346368409872 done gosh> (stream-head (accelerated-sequence euler-transform ln2-stream) 20) 1.0 0.7 0.6932773109243697 0.6931488693329254 0.6931471960735491 0.6931471806635636 0.6931471805604039 0.6931471805599445 0.6931471805599427 0.6931471805599454 +nan.0 +nan.0 +nan.0 +nan.0 +nan.0 +nan.0 +nan.0 +nan.0 +nan.0 +nan.0 done
3.66はパス
