Programmer Guide/Command Reference/EVAL/dct: Difference between revisions
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|inverse dct; the vector ''x'' is expanded with zeros to length ''n'' and the inverse transform is applied to the expanded vector (smoothing or liftering) | |inverse dct; the vector ''x'' is expanded with zeros to length ''n'' and the inverse transform is applied to the expanded vector (smoothing or liftering) | ||
|} | |} | ||
;See also: [[ | ;See also: [[../fft|fft]], [[../ifft|ifft]], [[../dft|dft]], [[../cepstrum|cepstrum]], [[../lpc|lpc]] | ||
[[ | [[../#Functions|<function list>]] | ||
Revision as of 10:31, 21 April 2011
Compute the forward or inverce discrete cosine transform (dct) of the input vector x. This function was implemented for the computation of the MFCC (mel-cepstrum coefficients).
- Usage
dct(x {, n {, dir)- x
- the data or coefficient vector
- n
- the number of dct coefficients to compute or to use (default=
nrow(x)); the meaning of this argument depends on the value of dir - dir
- the direction of the dct (default=0)
dir=0 -> forward dct otherwise -> inverse (or backward) dct
- Result
- A vector y containing the result of the transformation. In the following table NX is equal to
nrow(x).
dir x n dct-
lengthy nrow(y) description 0 data samples 0<n<=NXNX dct coefficients n forward dct; if n<NX only the first n coefficients are computed 1 dct coefficients 0<n<=NXNX data samples NX inverse dct; if n<NX only the first n coefficients of x are used, all other are set to 0 (smoothing or liftering) 1 dct coefficients n>NXn data samples n inverse dct; the vector x is expanded with zeros to length n and the inverse transform is applied to the expanded vector (smoothing or liftering)
