ex050900.m

stft(含:短时傅立叶变换 Gabor变换等)

% Chapter 05: Example 05.09: Circular symmetry property
%
subplot(1,1,1)
% a) plot x((-n))N
n = 0:10; x = 10*(0.8) .^ n;
y = x(mod(-n,11)+1);
subplot(2,1,1); stem(n,x); title('Original sequence')
xlabel('n'); ylabel('x(n)'); axis([-0.5,10.5,-1,11])
subplot(2,1,2); stem(n,y); title('Circularly folded sequence')
xlabel('n'); ylabel('x(-n mod 11)'); axis([-0.5,10.5,-1,11])
pause;
%print -deps2 me0509a.eps
%
% b) verify property
X = dft(x,11); Y = dft(y,11);
subplot(2,2,1); stem(n,real(X)); axis([-0.5,10.5,-5,50])
title('Real{DFT[x(n)]}'); xlabel('k');
subplot(2,2,2); stem(n,imag(X)); axis([-0.5,10.5,-20,20])
title('Imag{DFT[x(n)]}'); xlabel('k');
subplot(2,2,3); stem(n,real(Y)); axis([-0.5,10.5,-5,50])
title('Real{DFT[x((-n))11]}'); xlabel('k');
subplot(2,2,4); stem(n,imag(Y)); axis([-0.5,10.5,-20,20])
title('Imag{DFT[x((-n))11]}'); xlabel('k');
%print -deps2 me0509b.eps