38 lines
912 B
Scheme
38 lines
912 B
Scheme
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;; mandelbrot set
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(define mandel
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(lambda (rmin rmax imin imax res)
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(letrec
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((rdelta (- rmax rmin)) (idelta (- imax imin))
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(rdelta1 (/ rdelta res)) (idelta1 (/ idelta res))
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(pcolor
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(lambda (re im cre cim n)
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(if (or (> n 200) (> (+ (* re re) (* im im)) 4.0))
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(let
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((c (* 8 (remainder n 8)))
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(x (* res (/ (- cre rmin) rdelta)))
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(y (* res (/ (- cim imin) idelta))))
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(draw-color
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(* 255 (remainder n 2))
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(* 255 (remainder (quotient n 2) 2))
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(* 255 (remainder (quotient n 4) 2)))
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(draw-move x y)
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(draw-line (+ x 1) (+ y 1)))
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(pcolor
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(+ (- (* re re) (* im im)) cre)
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(+ (* 2 re im) cim)
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cre cim (+ 1 n)))))
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(iter
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(lambda (rep imp)
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(if (> rep rmax)
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(if (> imp imax) '()
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(iter rmin (+ imp idelta1)))
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(begin
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(pcolor 0 0 rep imp 0)
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(iter (+ rep rdelta1) imp))))))
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(iter rmin imin))))
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(mandel -1.5 0.5 -1.0 1.0 25)
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