## Wednesday, July 19, 2006

### Difference between DFT and FFT

A DFT (Discrete Fourier Transform) is simply the name given to the Fourier Transform when it is applied to digital (discrete) rather than an analog (continuous) signal. An FFT (Fast Fourier Transform) is a faster version of the DFT that can be applied when the number of samples in the signal is a power of two. An FFT computation takes approximately N * log2(N) operations, whereas a DFT takes approximately N^2 operations, so the FFT is significantly faster.

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Is the signal of FT and DFT discrete or continuous?

ReplyDeleteDiscrete

ReplyDeleteThanks!

ReplyDeletewhat do you mean by n*log2(n) operations and n^2 operations ?

ReplyDeleteIts nothing but number of multiplication n additions performed on signal in transform

ReplyDeletewhich one is better dft or fft

ReplyDeleteshouldnt it be (n/2)*log2 (n) for the fft?

ReplyDeletewhen we talk about big O, we only care n, n^2, etc.

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