Page 143 - Algorithm Collections for Digital Signal Processing Applications using MATLAB

3. Numerical Linear Algebra 131

14.2.2 M-file for daubechies 4 forward and inverse transformation

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daub4trans.m

i=0:1/127:1;
a=sin(2*pi*i)+sin(2*pi*100*i);
plot(a)
figure
s=length(a);
for i=1:1:log2(s) -2
a=[a a(1:2)];
i
temp=createdaubmatrix(length(a)-2)*a';
temp=temp(1:1:length(temp));
temp=reshape(temp,2,length(temp)/2);
approx{i}=temp(1,:);
det{i}=temp(2,:);
a=approx{i};
end
for k=1:1:(length(approx)-1)
subplot((length(approx)-1),1,k)
plot(approx{k})
title(strcat('approx',num2str(k)))
end
figure
for k=1:1:(length(approx)-1)
subplot((length(approx)-1),1,k)
plot(det{k})
title(strcat('detail',num2str(k)))
end