On 07/12/2010 12:36 PM, David Goldsmith wrote:
On Sun, Jul 11, 2010 at 6:18 PM, David Goldsmith <d.l.goldsmith@gmail.com <mailto:d.l.goldsmith@gmail.com>> 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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