MATLAB: How to create a 2D diagonal matrix from a 3D matrix with a generic dimension? It could be with a loop structure.

blkdiagdiagonal matrix

%%3D matrix k
    n=3;
    k=zeros(n)
    for a=1:n
        for b=1:n
            for c=1:n
                k(b,c,a)=c;
            end
        end
    end
using blkdiag could be obtained, however for a generic number of matrices n, this doesn't work.
    u=blkdiag(k(:,:,1),k(:,:,2),k(:,:,3))

Best Answer

Use a cell array and then something like,
c = arrayfun(@(x) k(:,:,x),1:n,'uni',0)
u = blkdiag(c{:})
u =
       1     2     3     0     0     0     0     0     0
       1     2     3     0     0     0     0     0     0
       1     2     3     0     0     0     0     0     0
       0     0     0     1     2     3     0     0     0
       0     0     0     1     2     3     0     0     0
       0     0     0     1     2     3     0     0     0
       0     0     0     0     0     0     1     2     3
       0     0     0     0     0     0     1     2     3
       0     0     0     0     0     0     1     2     3
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