www.pudn.com > bss_eval.zip > bss_make_lags.m

function S_lags=bss_make_lags(S,L); 
 
% create a matrix containing lagged versions of some signal(s). 
% 
% Usage: S_lags=bss_make_lags(S,L) 
% 
% Input: 
%   - S: n x T matrix containing the input signal(s), 
%   - L: number of lagged versions of the signal(s). 
% 
% Output: 
%   - S_lags: n*L x T matrix containing lagged versions of S, S_lags(t)= 
%   [s1(t) ; s1(t-1) ; ...; s1(t-L+1); ... ; sn(t) ; sn(t-1) ; ...; sn(t-L+1)] 
% 
% WARNINGS: 
%   * S_lags is zero-padded where necessary, 
%   * We use the conventions make_lags(S,0)=makes_lags(S,1)=S. 
% 
% Developers:  - Cedric Fevotte (cf269@cam.ac.uk) - Emmanuel Vincent 
% (vincent@ircam.fr) - Remi Gribonval (remi.gribonval@irisa.fr) 
 
[n,T]=size(S); 
 
if L==0 
    S_lags=S; 
else 
     
    N=n*L; 
    S_lags=zeros(N,T); 
    for i=1:N 
        q=floor((i-1)/L); 
        r=mod(i-1,L); 
        B=zeros(1,r+1); B(end)=1; 
        S_lags(i,:)=filter(B,1,S(q+1,:));     
    end 
     
end