MATLAB: Reshuffle a symmetric matrix

reshuffle

Hi all, I have a large symmetric matrix (600*600)and need to reshuffle the elements randomly while keeping the matrix symmetric.
Could anyone help? I shall be grateful.
Regards, Shafique

Best Answer

1.
sz = size(A);
B = zeros(sz);
vtl = nonzeros(tril(reshape(1:numel(A),sz)));
B(tril(true(sz))) = A(vtl( randperm(length(vtl))));
B = B + tril(B,-1).';
2. More variant - don't modify main diagonal
sz = size(A);
B = diag(diag(A));
vtl = nonzeros(tril(reshape(1:numel(A),sz),-1));
B(tril(true(sz),-1)) = A(vtl( randperm(length(vtl))));
B = B + tril(B,-1).';
3. OR main diagonal - zeros (modify last row of the previous cod)
B = B + tril(B,-1).'
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