[regenli]

load sumsin;
s=sumsin(1:1000);
figure;
subplot(511)
plot(s);
title('原始信号')
[c,l]=wavedec(s,5,'db4');
ca3=appcoef(c,l,'db4',3);
%利用upcoef重构信号
cd3=detcoef(c,l,3)
sca3=upcoef('a',ca3,'db4',3);
subplot(512);
plot(sca3);
title('ca3重构信号');
scd3=upcoef('d',cd3,'db4',3);
subplot(513);
plot(scd3);
title('cd3重构信号');
%%利用wrcoef重构信号
[c3,l3]=wavedec(s,3,'db4');
sca33=wrcoef('a',c3,l3,'db4',3);
subplot(514);
plot(sca33);
title('ca33重构信号');
scd33=wrcoef('d',c3,l3,'db4',3);
subplot(515);
plot(scd33);
title('cd33重构信号');

用upcoef和wrcoef对3尺度下的低频和高频重构出来的两组信号差别明显，重构方式上到底有什么不同