generate multi Diagonal matrices

I need help. I have beable to generate 100 of random matrices H. then try to get S diagonal matrix but it is not succesful as both s11=0, s22=0, however s33 value is correct.

N = 100;
for j=1:length(N)
   H = 0.5.*(randn(3,3, N) +(1i) * randn(3,3, N));
   
   for k=1:length(H)
       [S(3,3,k)]= svd(H(3,3,k)); 
       %[U(3,3,k),S(3,3,k),V(3,3,k)]= svd(matrices(3,3,k));
   end    
end

H(:,:,92) =

-0.3382 + 0.3345i 0.1304 + 0.0842i -0.4230 + 0.3986i

0.0729 - 0.5495i -0.3290 - 0.2820i -0.2131 - 0.1437i

0.3096 + 0.0466i 0.0022 - 0.3723i -0.2904 - 0.0265i

S(:,:,92) =

0 0 0

0 0 0

0 0 0.2916

Please advise

Thanks

Answer 1

[Bastian Arturo Romero Mardones]

In your code, you are only calculating the svd of the column 3 and row 3.

N = 100;
for j=1:length(N)
   H = 0.5.*(randn(3,3, N) +(1i) * randn(3,3, N));
   
   for k=1:length(H)
       [S(1,1,k)]= svd(H(1,1,k)); % row 1 column 1
       [S(2,2,k)]= svd(H(2,2,k)); % row 2 column 2       
       [S(3,3,k)]= svd(H(3,3,k)); % row 3 column 3
       %[U(3,3,k),S(3,3,k),V(3,3,k)]= svd(matrices(3,3,k));
   end    
end

[Seahawkgo]

Thanks a lot. It works.

[Bastian Arturo Romero Mardones]

Accept my answer please :D

Answer 2

[Christine Tobler]

The SVD is usually computed for a matrix, but you're only passing in a scalar on each call.

Is it possible you meant to pass in a page H(:, :, k) (which would be a 3-by-3 matrix) in every iteration?