多小波Matlab程序

malong 2006年8月22日浏览：143423 评论：2

多小波Matlab程序

function transf=dec1D_pe(fp,flt,maxlevel)
%transf=dec1D_pe(fp,flt,maxlevel)
%
% This function computes discrete multiwavelet transform of a preprocessed
% 1-dimensional signal. Boundaries are handled by periodic extension.
% For description of the algorithm see [SW].
%
% 对已经预滤波的信号进行多小波分解；
%
% Input:
% maxlevel integer, number of levels of decomposition
% flt string of characters, name of the filter;
% for possible names and short descriptions see coef.m
% fp r by n real array, preprocessed input data;
% r is the number of scaling functions,
% n must be of the form integer*2^maxlevel
%
% Output:
% transf r by n real array, multiscaling and multiwavelet coefficients;
% transf is organized as follows:
% columns 1 to n/2^maxlevel -- multiscaling coefficients
% columns n/2^maxlevel +1 to n/2^(maxlevel-1) -- coarsest
% multiwavelet coefficients
% ........................
% columns n/2+1 to n -- finest multiwavelet coefficient
%
% Example of Usage:
% transf=dec1D_pe(fp,'cl',5)

% Author: Vasily Strela
% COPYRIGHT 1997,98 by Vasily Strela

n=length(fp(1,:));

[L,H]=coef(flt);
[nf,ns]=size(L);
[nf,nw]=size(H);
ns=ns/nf;
nw=nw/nf;
if ns < nw
big=nw;
else
big=ns;
end
if fix(big/2) ~= big/2
big=(big+1)/2;
else
big=big/2;
end

i=1;
nss=1;
while L(:,nf*(i-1)+1:nf*i)==zeros(nf)
nss=nss+1;
i=i+1;
end
i=1;
nws=1;
while H(:,nf*(i-1)+1:nf*i)==zeros(nf)
nws=nws+1;
i=i+1;
end

transf=fp;
for lv=1:maxlevel
fp=zeros(nf,n);
fp=transf(:,1:n);
tr=zeros(nf,n);
for i=1:n/2-big
for j=nss:ns
tr(:,i)=tr(:,i)+L(:,nf*(j-1)+1:nf*j)*fp(:,2*i-2+j);
end
for j=nws:nw
tr(:,i+n/2)=tr(:,i+n/2)+H(:,nf*(j-1)+1:nf*j)*fp(:,2*i-2+j);
end
end

for i=n/2-big+1:n/2
for j=nss:ns
if 2*i-2+j>n
tr(:,i)=tr(:,i)+L(:,nf*(j-1)+1:nf*j)*fp(:,2*i-2+j-n);
else
tr(:,i)=tr(:,i)+L(:,nf*(j-1)+1:nf*j)*fp(:,2*i-2+j);
end
end
for j=nws:nw
if 2*i-2+j>n
tr(:,i+n/2)=tr(:,i+n/2)+H(:,nf*(j-1)+1:nf*j)*fp(:,2*i-2+j-n);
else
tr(:,i+n/2)=tr(:,i+n/2)+H(:,nf*(j-1)+1:nf*j)*fp(:,2*i-2+j);
end
end
end
transf(:,1:n)=tr;
n=n/2;
end

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