11 lines
231 B
APL
11 lines
231 B
APL
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fft←{
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N←⍴⍵
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N≤1:⍵
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(1|2⍟N)≠0:'Argument must be a power of 2 in length'
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even←fft(N⍴0 1)/⍵
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odd←fft(N⍴1 0)/⍵
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k←N÷2
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T←even×*(0J¯2×(○1)×(¯1+⍳k)÷N)
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(odd+T),odd-T
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}
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