# How to explore off diagonal elements in matrices without avoiding the for loop?

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Zeynab Mousavikhamene on 15 Apr 2020
Edited: Vasilis Chasiotis on 8 Oct 2020
I need to search if the value of off diagonal elements of many matrices are larger than a specific number. Was wondering if I can do that without using a loop.
James Tursa on 15 Apr 2020
Square matrices? Just the nearest off-diagonals?

Peng Li on 15 Apr 2020
Not sure if many matrices share the same size. Anyway if you store these matrices in a cell you prob have a chance using cellfun to accomplish this I think. You can use triu or tril to get all off diagonal elements.

Vasilis Chasiotis on 8 Oct 2020
Edited: Vasilis Chasiotis on 8 Oct 2020
A = randn(n,n); % a n-by-n matrix of random numbers
idx = eye(n,n); % the identity matrix of order n
if all( A(~idx) > K ) % check if all the off-diagonal elements of A are greater than K
...
end
So, you check all the off-diagonal elements of A without using a loop.

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