Nested Loop with Matrices - Transfer Matrix Method

Dear Community,

My problem has a two step question

Question 1) I have to produce a 2x3 system where each variable contains a 4x4 matrix (attached you will see a picture)

As you can see, this is the system (Global 2x3 while each variable has an 4x4 associated matrix)

for that I proposed the following script

l = 5;

J = 30;

E = 131960;

Matrix_1 = eye(4);

Matrix_0 = zeros(4,4);

B = [1,-l,(-l^3)/(J*E),(-l^2)/(J*E);0,1,(l^2)/(J*E),(l)/(J*E);0,0,1,0;0,0,l,1];

for i = 1:2

for j = 1:3

if A(i,j)==A(i,i)

A = [B] ;

elseif A(i,j) == A(i,i+1)

A = [B,-Matrix_1];

else A(i,j) = A(i,j);

A = [Matrix_0];

end

end

end

Point/Question 2) I need to integrate the whole system using Runge Kutta.

Problems :

1) the script runs without problem but I can't make the former assign to each position its respective associated matrix and store. How can I do that?

2) the problem is not Runge Kutta per se, I used it in the past. In this case, this system is related to a beam and therefore it has boundary conditions. Hence, I just have some initial zero values and final zero values and I dont know how to solve that. How would you solve it?

thanks for your Help!