forked from KolibriOS/kolibrios
29 lines
1.2 KiB
Plaintext
29 lines
1.2 KiB
Plaintext
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This is a draft version of my Fast Hartley Transform (FHT) routine for KolibriOS
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Hartley transform is a real-basis version of well-known Fourier transform:
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1) basis function: cas(x) = cos(x) + sin(x);
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2) forward transform: H(f) = sum(k=0..N-1) [X(k)*cas(kf/(2*pi*N))]
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3) reverse transform: X(k) = 1/N * sum(f=0..N-1) [H(f)*cas(kf/(2*pi*N))]
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FHT is known to be faster than most conventional fast Fourier transform (FHT) methods.
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It also uses half-length arrays due to no need of imaginary data storage.
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FHT can be easily converted to FFT (and back) with no loss of information.
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Most of general tasks FFT used for (correlation, convolution, energy spectra, noise
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filtration, differential math, phase detection ect.) may be done directly with FHT.
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====================================================================================
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Copyright (C) A. Jerdev 1999, 2003 and 2010.
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The code can be used, changed and redistributed in any KolibriOS application
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with only two limitations:
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1) the author's name and copyright information cannot be deleted or changed;
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2) the code is not allowed to be ported to or distributed with other operation systems.
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18/09/2010
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Artem Jerdev <kolibri@jerdev.co.uk>
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