load trees.mat
whos
figure(1),colormap(gray)
image(X)
[U,S,V]=svd(X); 
A=zeros(size(X)); 
figure(2),colormap(gray)
for i=1:50,A=A+S(i,i)*U(:,i)*V(:,i)';image(A),pause,end
figure(3)
plot(diag(S))