Hello JaeSung,
In this situation, I would suggest the usage of cell arrays to store your 1000 by 1000 matrices (topologies). You can first initialize the cell array 'B' using the code below:
B = cell(10,10);
Afterwards, you can assign data to the cell array using cell array syntax:
A1 = eye(1000,1000);
B{1,1} = A1;
You can then also access the cell array data using the same syntax:
disp(B{1,1});
You can read more about cell arrays in the documentation page below:
https://www.mathworks.com/help/matlab/ref/cell.html
