load  trsin;
x = trsin;
subplot(711);
plot(x);
axis tight;
ylabel('x');
% 使用db5小波對信號進行6層分解
[c,l]=wavedec(x,6,'db5');
for i=1:6
    % 對分解的第6層到第1層的低頻系數近行重構
    a = wrcoef('a',c,l,'db5',7-i);
    subplot(7,1,i+1);
    plot(a);
    axis tight;
    ylabel(['a',num2str(7-i)]);       
end
figure(2);
subplot(711);
plot(x);
axis tight;
ylabel('x');
for i=1:6
     % 對分解的第6層到第1層的高頻系數近行重構
    d = wrcoef('d',c,l,'db5',7-i);
    subplot(7,1,i+1);
    plot(d);
    axis tight;
    ylabel(['d',num2str(7-i)]);
end