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- #!/usr/bin/ruby
- func fft(arr) {
- arr.len == 1 && return arr
- var evn = fft([arr[^arr -> grep { .is_even }]])
- var odd = fft([arr[^arr -> grep { .is_odd }]])
- var twd = (Num.tau.i / arr.len)
- ^odd -> map {|n| odd[n] *= exp(twd * n) }
- (evn »+« odd) + (evn »-« odd)
- }
- var cycles = 3
- var sequence = 0..15
- var wave = sequence.map {|n| sin(n * Num.tau / sequence.len * cycles) }
- say "wave:#{wave.map{|w| '%6.3f' % w }.join(' ')}"
- say "fft: #{fft(wave).map { '%6.3f' % .abs }.join(' ')}"
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