annotate dsp/realfft.m @ 47:82075c94eed1
adding a bunch of stuff, including graphics and pitch toolboxes.
| author |
samer |
| date |
Sat, 17 Jan 2015 15:20:35 +0000 |
| parents |
c3b0cd708782 |
| children |
|
| rev |
line source |
|
samer@32
|
1 function [y,f] = realfft(x,nfft)
|
|
samer@32
|
2 % realfft - Do FFT assuming real data, returning complex half spectrum
|
|
samer@32
|
3 %
|
|
samer@32
|
4 % realfft ::
|
|
samer@32
|
5 % [[L,T]->real] ~'sequence of T L-point frames',
|
|
samer@32
|
6 % N:natural ~'FFT size'
|
|
samer@32
|
7 % -> [[M,T]->complex] ~'sequence of T M-point complex spectra',
|
|
samer@32
|
8 % [[M]] ~'normalised centre frequency for each bin'.
|
|
samer@32
|
9 %
|
|
samer@32
|
10 % Note that M=dftbins(N).
|
|
samer@32
|
11
|
|
samer@32
|
12 % apply the window and do FFT on each column, then
|
|
samer@32
|
13 % assume it's a real signal and discard half the bins
|
|
samer@32
|
14 y = fft(x,nfft);
|
|
samer@32
|
15 select=1:dftbins(nfft);
|
|
samer@32
|
16 y = y(select,:);
|
|
samer@32
|
17 % compute the normalised frequency for each bin
|
|
samer@32
|
18 f=(select-1)/nfft;
|
