Article View: comp.dsp
Article #449Re: Hartley xform
From: Hubert Matthews
Date: Tue, 10 Oct 1989 23:28
Date: Tue, 10 Oct 1989 23:28
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What's all the fuss about? Unless I'm much mistaken (and I don't think I am :->), this property of the FT is well known. If you take the FT of purely real data, you get a transform that is Hermitian: the real part of the transform is symmetrical about zero, and the imaginary part is asymmetrical. Thus, you need store only half of each part of the transform, as the other half may be deduced using symmetry. This is exactly how the NAG library FFT routine for real input data returns the result. It sounds like Bracewell is patenting common knowledge. -- Hubert Matthews ...helping make the world a quote-free zone... hjm@cernvax.cern.ch hjm@vxomeg.decnet.cern.ch ...!mcvax!cernvax!hjm
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!bloom-beacon!eru!luth!sunic!mcsun!cernvax!hjm From: hjm@cernvax.UUCP (Hubert Matthews) Newsgroups: comp.dsp Subject: Re: Hartley xform Message-ID: <1115@cernvax.UUCP> Date: 10 Oct 89 23:28:06 GMT References: <wZ_UwgC00UkM8KM0RN@andrew.cmu.edu> Reply-To: hjm@cernvax.UUCP (Hubert Matthews) Organization: CERN European Laboratory for Particle Physics, CH-1211 Geneva, Switzerland Lines: 17