34 lines
729 B
Julia
34 lines
729 B
Julia
using FFTW
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function dct(f)
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function a(u, N)
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if u == 0
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sqrt(1/N)
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else
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sqrt(2/N)
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end
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end
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if ndims(f) == 1
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N = length(f)
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[a(u, N) * sum([x * cos(pi * u * (2i - 1)/ (2N)) for (i, x) in enumerate(f)]) for u=0:N - 1]
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elseif ndims(f) == 2
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N, M = size(f)
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[a(u, N) * a(v, M) * sum([f[x+1, y+1] * cos(pi * u * (2x + 1)/ (2N)) * cos(pi * v * (2y + 1) / (2M)) for x=0:N-1, y=0:M-1]) for u=0:N - 1, v=0:M-1]
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else
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error("What the hell man?")
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end
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end
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if abspath(PROGRAM_FILE) == @__FILE__
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display(dct(1:8))
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println()
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display(FFTW.dct(1:8))
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println()
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display(dct([(i-1)*8 + j for i=1:8, j=1:8]))
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println()
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display(FFTW.dct([(i-1)*8 + j for i=1:8,j=1:8]))
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println()
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end
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