51 lines
1.4 KiB
Scheme
51 lines
1.4 KiB
Scheme
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;;; MBROT -- Generation of Mandelbrot set fractal.
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(define (count r i step x y)
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(let ((max-count 64)
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(radius^2 16.0))
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(let ((cr (FLOAT+ r (FLOAT* (exact->inexact x) step)))
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(ci (FLOAT+ i (FLOAT* (exact->inexact y) step))))
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(let loop ((zr cr)
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(zi ci)
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(c 0))
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(if (= c max-count)
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c
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(let ((zr^2 (FLOAT* zr zr))
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(zi^2 (FLOAT* zi zi)))
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(if (FLOAT> (FLOAT+ zr^2 zi^2) radius^2)
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c
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(let ((new-zr (FLOAT+ (FLOAT- zr^2 zi^2) cr))
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(new-zi (FLOAT+ (FLOAT* 2.0 (FLOAT* zr zi)) ci)))
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(loop new-zr new-zi (+ c 1))))))))))
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(define (mbrot matrix r i step n)
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(let loop1 ((y (- n 1)))
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(if (>= y 0)
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(let loop2 ((x (- n 1)))
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(if (>= x 0)
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(begin
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(vector-set! (vector-ref matrix x) y (count r i step x y))
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(loop2 (- x 1)))
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(loop1 (- y 1)))))))
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(define (test n)
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(let ((matrix (make-vector n)))
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(let loop ((i (- n 1)))
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(if (>= i 0)
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(begin
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(vector-set! matrix i (make-vector n))
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(loop (- i 1)))))
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(mbrot matrix -1.0 -0.5 0.005 n)
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(vector-ref (vector-ref matrix 0) 0)))
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(define (main . args)
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(run-benchmark
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"mbrot"
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mbrot-iters
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(lambda (result) (equal? result 5))
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(lambda (n) (lambda () (test n)))
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75))
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