clf;
clear;
%調入含突變點的信號
load nearbrk;
x=nearbrk;
N=length(x);
t=1:N;
figure(1);
plot(t,x,'LineWidth',2);xlabel('時間 t/s');ylabel('幅值 A');
%一維小波分解
[c,l] = wavedec(x,5,'db2');
%重構第5層逼近系數
a5 = wrcoef('a',c,l,'db2',5);
%重構第1～5層細節系數
d5 = wrcoef('d',c,l,'db2',5);
d4 = wrcoef('d',c,l,'db2',4);
d3 = wrcoef('d',c,l,'db2',3);
d2 = wrcoef('d',c,l,'db2',2);
d1 = wrcoef('d',c,l,'db2',1);
%顯示重構系數和細節系數
figure(2)
subplot(6,1,1);plot(d5,'LineWidth',2);ylabel('d5');
subplot(6,1,2);plot(d4,'LineWidth',2);ylabel('d4');
subplot(6,1,3);plot(d3,'LineWidth',2);ylabel('d3');
subplot(6,1,4);plot(d2,'LineWidth',2);ylabel('d2');
subplot(6,1,5);plot(d1,'LineWidth',2);ylabel('d1');
subplot(6,1,6);plot(a5,'LineWidth',2);ylabel('a5');
xlabel('時間 t/s');