fft

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Fast fourier transform.


Usage 1
fft(x)
x
signal vector or matrix; if x is a matrix a spectrum of each column is computed
Result
A matrix y with ncol(x) columns and L+2 rows, where each column y[*,j] contains the complex spectrum of the column (channel) x[*,i]. The transformation length L is set to npow2(nrow(x)).

Usage 2
fft(x, n {, ytype, poffset, prange, aref})
x
signal vector or matrix; if x is a matrix a spectrum of each column is computed
n
desired length of analysis window;
  • If n < nrow(x), the analysis window length L is set to nrow(x), otherwise L is set to n.
  • If the analysis window length L is a power of 2 (L=2^M), the fft algorithm is used, otherwise the dft is used.


See also
ifft, dft, dct, cepstrum, lpc

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