MATLAB: How to create a symmetric random matrix

Question

Hello,

I need to create a random matrix meeting the following conditions:

– The values on the main diagonal are between a given range (e.g., 0 to 1000000)

– Each value on the diagonal is randomly distributed/spread in its corresponding row and column vectors.

– The matrix is symmetric (that is to say, corresponding values in upper and lower triangles are the same)

Any help will be highly appreciated.

Best,

M

Answer 1

Let the random matrix to be generated be called M and its size be NxN.

   d = 1000000*rand(N,1); % The diagonal values
   t = triu(bsxfun(@min,d,d.').*rand(N),1); % The upper trianglar random values
   M = diag(d)+t+t.'; % Put them together in a symmetric matrix

If you want whole numbers, apply the 'floor' function to 'd' and then after computing 't', apply it to 't'.