; Triangle wave with a period of 1 second
(define (tri t)
	(let ((m (floor-remainder (+ t (/ 1 4)) 1)))
		(if (< m 1/2)
			(- (* 4 m) 1)
			(- 3 (* 4 m)))))

; Square wave with a period of 1 second
(define (square t)
	(let ((m (floor-remainder t 1)))
		(if (< m 0.5) 1 -1)))

; Creates a note
(define (note freq start len)
	(lambda (t) (
		if (or (< t start) (>= t (+ start len)))
			0
			(* 1/4 (tri (* t freq))))))

; Gets the frequency of a particular pitch
(define (getfreq octave pitch)
	(* 55 (ash 1 octave) (expt 2 (/ pitch 12))))