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  1. #lang racket
  2.  
  3. (require plot/no-gui)
  4.  
  5. (define enumerate
  6.   (case-lambda
  7.     ((seq) (enumerate seq 0))
  8.     ((seq start) (map (lambda (x y)
  9.                         (cons x y))
  10.                       (range start (+ (length seq) start))
  11.                       seq))))
  12.  
  13. (define seq
  14.   (case-lambda
  15.     ((a b d x0 y0)
  16.      (define s
  17.        (stream-cons (vector x0 y0)
  18.                     (stream-map (match-lambda
  19.                                   ((vector x y)
  20.                                    (vector (+ (* a x) (* b y)
  21.                                               (/ d (add1 (expt x 2))))
  22.                                            (- x))))
  23.                                 s)))
  24.      s)
  25.     ((a)
  26.      (seq a 0.9 15 1 0))))
  27.  
  28. (define (transpose pos ksx ksy)
  29.   (match-let (((vector x y) pos))
  30.     (let ((coef (/ 1 (sqrt 2))))
  31.       (vector (* coef (+ x y) ksx)
  32.               (* coef (+ (- x) y) ksy)))))
  33.  
  34. (define (chaos a ksx ksy)
  35.   (stream-map (lambda (pos)
  36.                 (transpose pos ksx ksy))
  37.               (seq a)))
  38.  
  39. (define *data*
  40.   '((-0.15 0.96 1.04)
  41.     (-0.32 0.92 1.08)
  42.     (-0.70 0.81 1.16)
  43.     (-1.09 0.67 1.24)
  44.     (-1.47 0.51 1.32)
  45.     (-1.66 0.41 1.35)))
  46.  
  47. (module+ main
  48.   (parameterize ((plot-x-label #f)
  49.                  (plot-y-label #f))
  50.     (for-each (match-lambda
  51.                 (`(,i ,a ,ksx ,ksy)
  52.                  (plot-file
  53.                   (points
  54.                    (stream->list
  55.                     (stream-take
  56.                      (chaos a ksx ksy)
  57.                      60000)))
  58.                   (format "./chaos~a.png" i))))
  59.               (enumerate *data*))))
  60.  
Success #stdin #stdout 0.3s 57904KB
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https://ideone.com/5lscFf
language:
Racket (racket 7.0)
created:
1 year ago
visibility:
secret

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