f2dc2027f6
in the original GitHub fork: https://github.com/ntoronto/racket Some things about this are known to be broken (most egregious is that the array tests DO NOT RUN because of a problem in typed/rackunit), about half has no coverage in the tests, and half has no documentation. Fixes and docs are coming. This is committed now to allow others to find errors and inconsistency in the things that appear to be working, and to give the author a (rather incomplete) sense of closure.
61 lines
2.5 KiB
Racket
61 lines
2.5 KiB
Racket
#lang typed/racket
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(require typed/racket/base
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math/array
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typed/rackunit)
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(: mandelbrot (Float Integer -> (Array Integer)))
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(define (mandelbrot step max-iters)
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(define xs (sequence->list (in-range -2.0 0.800001 step)))
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(define ys (sequence->list (in-range -1.4 1.400001 step)))
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(define x ((inst list*->array Float) xs flonum?))
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(define y (array-slice-ref ((inst list*->array Float) ys flonum?) (list ::... (::new 1))))
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(define c (array->fcarray (array+ x (array-scale y +1.0i))))
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(define-values (z divtime)
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(for/fold: ([z : FCArray c]
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[divtime : (Array Integer) (make-array (array-shape c) max-iters)]
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) ([i (in-range max-iters)])
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(let ([z (fcarray+ (fcarray-sqr z) c)])
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(values z (array-strict (array-if (array-and (flarray> (fcarray-magnitude z) (flarray 4.0))
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(array= divtime (array max-iters)))
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(array i)
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divtime))))))
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divtime)
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(check-equal? (mandelbrot 0.2 20)
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(array [[0 1 1 1 1 1 1 1 1 1 1 1 1 1 1]
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[1 1 1 1 1 1 2 2 2 3 2 2 1 1 1]
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[1 1 1 1 1 2 2 2 3 6 20 3 2 1 1]
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[1 1 1 2 2 2 3 4 5 20 17 4 3 2 1]
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[1 1 2 2 3 3 4 11 20 20 20 10 14 2 2]
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[1 2 3 4 6 6 6 20 20 20 20 20 9 3 2]
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[2 3 4 6 18 20 14 20 20 20 20 20 20 3 2]
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[20 20 20 20 20 20 20 20 20 20 20 20 5 3 2]
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[2 3 4 6 18 20 14 20 20 20 20 20 20 3 2]
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[1 2 3 4 6 6 6 20 20 20 20 20 9 3 2]
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[1 1 2 2 3 3 4 11 20 20 20 10 14 2 2]
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[1 1 1 2 2 2 3 4 5 20 17 4 3 2 1]
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[1 1 1 1 1 2 2 2 3 6 20 3 2 1 1]
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[1 1 1 1 1 1 2 2 2 3 2 2 1 1 1]
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[0 1 1 1 1 1 1 1 1 1 1 1 1 1 1]]))
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(begin
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(require images/flomap)
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(: array->flomap ((Array Real) -> flomap))
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(define (array->flomap arr)
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(let ([arr (array->flarray arr)])
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(define ds (array-shape arr))
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(match ds
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[(vector h w) (flomap (flarray-data arr) 1 w h)]
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[(vector h w c) (flomap (flarray-data arr) c w h)]
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[_ (error 'array->flomap "expected array with 2 or 3 dimensions; given shape ~e" ds)])))
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(define fm
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(array->flomap
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(time (mandelbrot 0.007 20))))
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(flomap-size fm)
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(flomap->bitmap (flomap-normalize fm)))
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