load noissin;                                          
s=noissin(1:1000);                             
[c,l]=wavedec(s,3,'db4');                    
[cd1,cd2,cd3]=detcoef(c,l,[1,2,3]);            
ca3=appcoef(c,l,'db4',3);                        
subplot(511);plot(1:1000,s);title('s');            
subplot(512);plot(1:l(1),ca3);title('ca3');           
subplot(513);plot(1:l(2),cd3);title('cd3');
subplot(514);plot(1:l(3),cd2);title('cd2');
subplot(515);plot(1:l(4),cd1);title('cd1');