Optimizing a matrix of values

Hi, I need help in optimizing a matrix of values. Assuming a 3x3 matrix, I would have this matrix:

I needed the values of A to F be optimized. What I would usually do is to just take [A B C D E F] as an input value and call it a day. To be fair, this works decently.

My main issue is that my matrix usually changes size, ie. it becomes this:

I will have to change the input to [A B] this time. My question, is, is there a more elegant way of doing these things: Is there a way for me to simply plug in the two matrices without reshaping them and forcing 0 on the diagonal?

Answer 1

[Matt J]

You could define the whole matrix as unknown, but with diagonal elements bound to zero:

LB=-inf(n); 
LB(1:n+1:end)=0;
UB=-LB;

M=optimvar('M',[n,n],'Lower',LB,'Upper',UB);

Answer 2

[madhan ravi]

a = zeros(3); 
[m, n] = size(a);
a(~diag(1 : m)) = 1 : m * n - m;
a.'

[madhan ravi]

a = zeros(2); 
[m, n] = size(a);
a(~diag(1 : m)) = m * n - m : -1 : 1 
%a(~diag(1 : m)) = flip(your_input)

[madhan ravi]

where 1 : m * n - m is your input