MATLAB中的wavedec、wrcoef函数简析

小波分解函数：

[C,L] = wavedec(X,N,'wname')；

returns the wavelet decomposition of the signal X at level N, using 'wname'. N must be a strictly positive integer. The output decomposition structure contains the wavelet decomposition vector Cand the bookkeeping vector L.

The structure is organized as in this level-3 decomposition example.

 

wrcoef小波重构函数：

采用补零的扩展模式，装载一维信号

X = wrcoef('type',C,L,'wname',N)；

computes the vector of reconstructed coefficients, based on the wavelet decomposition structure [C,L], at level N. 'wname' is a string containing the wavelet name.

 

example:

% wavelet test
% cole3
% 2009.7.26
t=0:1:127;
y=sin(t/10);
plot(y);
z=sin(t/5);
plot(z);
for i = 1:64
    y(64+i) = z(i);
end
plot(y);

%f=fft(y);
%plot(abs(f));

[d,a]=wavedec(y,3,'db5');
subplot(211);plot(a);
subplot(212);plot(d);
a3=wrcoef('a',d,a,'db5',3);
d3=wrcoef('d',d,a,'db5',3);
d2=wrcoef('d',d,a,'db5',2);
d1=wrcoef('d',d,a,'db5',1);
subplot(411);plot(a3);
subplot(412);plot(d3);
subplot(413);plot(d2);
subplot(414);plot(d1);