RosettaCodeData/Task/Cumulative-standard-deviation/Scheme/cumulative-standard-deviati...

16 lines
487 B
Scheme

(define (standart-deviation-generator)
(let ((nums '()))
(lambda (x)
(set! nums (cons x nums))
(let* ((mean (/ (apply + nums) (length nums)))
(mean-sqr (lambda (y) (expt (- y mean) 2)))
(variance (/ (apply + (map mean-sqr nums)) (length nums))))
(sqrt variance)))))
(let loop ((f (standart-deviation-generator))
(input '(2 4 4 4 5 5 7 9)))
(unless (null? input)
(display (f (car input)))
(newline)
(loop f (cdr input))))