mand2.rkt

#lang racket

(define (mandelbrot/old iterations x y n)
  (let ([ci (- (/ (* 2.0 y) n) 1.0)]
        [cr (- (/ (* 2.0 x) n) 1.5)])
    (let loop ([i 0] [zr 0.0] [zi 0.0])
      (if (> i iterations)
          i
          (let ([zrq (* zr zr)]
                [ziq (* zi zi)])
            (cond
              [(> (+ zrq ziq) 4) i]
              [else (loop (add1 i)
                          (+ (- zrq ziq) cr)
                          (+ (* 2 zr zi) ci))]))))))
 
(define (mandelbrot/new iterations x y n)
  (let ([ci (- (/ (* 2.0 y) n) 1.0)]
        [cr (- (/ (* 2.0 x) n) 1.5)])
    (let loop ([i 0] [zr 0.0] [zi 0.0])
      (if (> i iterations)
          i
          (let ([zrq (* zr zr)]
                [ziq (* zi zi)])
            (cond
              [(> (+ zrq ziq) 4.0) i]
              [else (loop (add1 i)
                          (+ (- zrq ziq) cr)
                          (+ (* 2.0 zr zi) ci))]))))))
 
 
(require future-visualizer)
(visualize-futures
 (let ([f (future (lambda () (mandelbrot/new 10000000 62 501 1000)))])
   (list (mandelbrot/new 10000000 62 500 1000)
         (touch f))))