Replace the diagonal with NaN in this 5x5 matrix

a=[1 0 0 0 0;0 1 0 0 0;0 0 1 0 0;0 0 0 1 0;0 0 0 0 1]
function y_diagonal =replace_NaN(x)
y=x;
end

Answer 1

[Allen]

Another approach to this if you know that your original matrix will always be a square matrix. You can use the following:

a(eye(size(a))==1) = nan;

Answer 2

[James Tursa]

You could use linear indexing for the diagonal. E.g., assuming x is square you could add this line to your function:

y(1:size(x,1)+1:end) = nan;