load nelec;
indx = 1:1024; 
x = nelec(indx);
%用小波函數haar對信號進行5層分解
[c,l] = wavedec(x,5,'haar'); 
%獲取信號壓縮的閥值
[thr,nkeep] = ddencmp('cmp','wv',x);   
%對信號進行壓縮
xd = wdencmp('gbl',c,l,'haar',5,thr,'s',1);   
subplot(211), plot(indx,x); 
title('原始信號');
subplot(212), plot(indx,xd); 
title('壓縮后的信號');