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Rev | Author | Line No. | Line |
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2210 | art_zh | 1 | This is a draft version of my Fast Hartley Transform (FHT) routine for KolibriOS |
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3 | Hartley transform is a real-basis version of well-known Fourier transform: |
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5 | 1) basis function: cas(x) = cos(x) + sin(x); |
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6 | 2) forward transform: H(f) = sum(k=0..N-1) [X(k)*cas(kf/(2*pi*N))] |
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7 | 3) reverse transform: X(k) = 1/N * sum(f=0..N-1) [H(f)*cas(kf/(2*pi*N))] |
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9 | FHT is known to be faster than most conventional fast Fourier transform (FHT) methods. |
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10 | It also uses half-length arrays due to no need of imaginary data storage. |
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12 | FHT can be easily converted to FFT (and back) with no loss of information. |
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13 | Most of general tasks FFT used for (correlation, convolution, energy spectra, noise |
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14 | filtration, differential math, phase detection ect.) may be done directly with FHT. |
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16 | ==================================================================================== |
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18 | Copyright (C) A. Jerdev 1999, 2003 and 2010. |
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20 | The code can be used, changed and redistributed in any KolibriOS application |
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21 | with only two limitations: |
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23 | 1) the author's name and copyright information cannot be deleted or changed; |
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25 | 2) the code is not allowed to be ported to or distributed with other operation systems. |
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27 | 18/09/2010 |
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28 | Artem Jerdev |