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I just had a question about combining elements of matrices.

In the matlab documentation, there was a function called triu and tril that extracts the upper and lower components of a matrix, respectively. I was wondering if there was a way to copy the elements of the upper triangle to the lower triangle portion of the symmetric matrix (or visa versa)?

EG-

haha =

1 0 0

1 1 0

1 0 1 ->

function (copy lower half to upper half)(haha)

1 1 1

1 1 0

1 0 1

any help will be appreciated. thanks!

UPDATE- I found an article from a website that wrote the method below, but I can't entirely understand it, and moreover, don't know how I can apply this for the lower matrix, copying to the upper half. I was hoping to be able to understand the code to be able to convert, but I can't understand the code.. and testing the code gives me a mupadmex error.

here it is:

[ i j ] = find(tril(ones(m), 1)); %Trick to get indices.

D = zeros(m, m); %Initialise output matrix.

D( i + m*(j-1) )= sqrt(sum(abs( kmat(i,:) - kmat(j,:) ).^2, 2));

D( j + m*(i-1) )= D( i + m*(j-1) );

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# [Matlab]Copy Lower Triangle of symmetric matrix to Upper Triangle(or visa versa)

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