;; (cusp-n rate freq a b xi)
;; (cusp-l rate freq a b xi)

;; freq - iteration frequency in Hertz
;; a, b - equation variables
;; xi   - initial value of x

;; Cusp map chaotic generator.  Non- and linear- interpolating sound
;; generator based on the difference equation:

;; xn+1 = a - b*sqrt(|xn|)

(define cusp_ cusp-l)

;; vary frequency

(let ((x (mouse-x kr 20 sample-rate 0 0.1)))
  (audition (out 0 (mul (cusp_ ar x 1.0 1.99 0) 0.3))))

;; mouse-controlled params

(let ((x (mouse-x kr 0.9 1.1 1 0.1))
      (y (mouse-y kr 1.8 2 1 0.1)))
  (audition (out 0 (mul (cusp_ ar (fdiv sample-rate 4) x y 0) 0.3))))

;; as a frequency control

(let* ((x (mouse-x kr 0.9 1.1 1 0.1))
       (y (mouse-y kr 1.8 2 1 0.1))
       (f (mul-add (cusp_ ar 40 x y 0) 800 900)))
  (audition (out 0 (mul (sin-osc ar f 0.0) 0.4))))