www.gusucode.com > wavelet 源码程序 matlab案例代码 > wavelet/VisualizingWaveletsWaveletPacketsandWaveletFiltersExample.m

    %% Visualizing Wavelets, Wavelet Packets, and Wavelet Filters  
% This example shows how to use |wfilters|, |wavefun|, and |wpfun| to obtain
% the filters, wavelet, or wavelet packets corresponding to a particular
% wavelet family. You can visualize 2-D separable wavelets with |wavefun2|.   

%% 
% Obtain the decomposition (analysis) and reconstruction (synthesis) filters
% for the biorthogonal spline wavelet filters with 3 vanishing moments in
% the reconstruction filter and 5 vanishing moments in the decomposition
% filter. 
[LoD,HiD,LoR,HiR] = wfilters('bior3.5');
subplot(221);
stem(LoD,'markerfacecolor',[0 0 1]); title('Lowpass Decomposition Filter');
subplot(222);
stem(LoR,'markerfacecolor',[0 0 1]); title('Lowpass Reconstruction Filter');
subplot(223);
stem(HiD,'markerfacecolor',[0 0 1]); title('Highpass Decomposition Filter');
subplot(224);
stem(HiR,'markerfacecolor',[0 0 1]); title('Highpass Reconstruction Filter');     

%% 
% Visualize the real-valued Morlet wavelet. There is no associated scaling
% function. 
figure;
[psi,xval] = wavefun('morl');
plot(xval,psi,'linewidth',2);
title('$\psi(x) = e^{-x^2/2} \cos{(5x)}$','Interpreter','latex',...
     'fontsize',14);  
%% 
% Obtain the first 4 wavelet packets for the Daubechies least-asymmetric
% wavelet with 4 vanishing moments, |sym4|. 
[wpws,x] = wpfun('sym4',4,10);
  for nn = 1:size(wpws,1)
    subplot(3,2,nn)
    plot(x,wpws(nn,:)); axis tight;
    title(['W',num2str(nn-1)]);
end