FFT - Teradata Vantage

Machine Learning Engine Analytic Function Reference

Product
Teradata Vantage
Release Number
8.00
1.0
Published
May 2019
Language
English (United States)
Last Update
2019-11-22
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B700-4003
lifecycle
previous
Product Category
Teradata Vantage™

The FFT function uses a Fast Fourier Transform (FFT) algorithm to compute the discrete Fourier Transform (DFT) of each signal in one or more input table columns. A signal can be either real or complex, and can have one, two, or three dimensions. If the signal length is not a power of two, the function either pads or truncates it to the closest power of two.

This is the DFT of a time sequence of length N, 0..N-1:
X(k) = Xk(N - k)

where k ϵ 0..N-1.

Therefore:
  • The FFT of a time sequence of length 1 is the one-element sequence itself.
  • The FFT of a time sequence of length 2 has only real values.
  • The FFT of a time sequence of length 4 or greater has conjugate symmetry.

To recover the original signals, use the IFFT function.