On 07/12/2010 12:36 PM, David Goldsmith wrote: > On Sun, Jul 11, 2010 at 6:18 PM, David Goldsmith > <[email protected] <mailto:[email protected]>> wrote: > > In numpy.fft we find the following: > > "Then A[1:n/2] contains the positive-frequency terms, and A[n/2+1:] > contains the negative-frequency terms, in order of decreasingly > negative frequency." > > Just want to confirm that "decreasingly negative frequency" means > ..., A[n-2] = A_(-2), A[n-1] = A_(-1), as implied by our definition > (attached). > > DG > > > And while I have your attention :-) > > "For an odd number of input points, A[(n-1)/2] contains the largest > positive frequency, while A[(n+1)/2] contains the largest [in absolute > value] negative frequency." Are these not also termed Nyquist > frequencies? If not, would it be incorrect to characterize them as "the > largest realizable frequencies" (in the sense that the data contain no > information about any higher frequencies)? > > DG > I would find the term the "largest realizable frequency" quite confusing. Realizing is a too ambiguous term IMO. It's the largest possible frequency contained in the array, so Nyquist frequency would be correct IMO.
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