MATLAB: Good method to store pyramid shaped cell array

cell

Hi all,
I need to store some matrices in a cell, say I have 4 matrices: e1, e2, e3, e4, I need to compute the product of the matrix transpose and the matrix itself like:
e1' * e1; e1' * e2;
e2' * e2; e2' * e3;
e3' * e3; e3' * e4;
e4' * e4;
So the matrix transpose product itself, and the matrix transpose multiply the next matrix. I can use a 4-by-2 cell to store these, but the last cell element would be void, any better ways? I'd like to keep the hierarchical structure. Cheers!
Edit: I'm sorry, I should have made the question clearer. I just generate a 4-by-2 cell array and store these in it, leaving the last cell element void. I think it is fine for now.

Best Answer

You can make use the of the linear indexing of MATLAB. Basically 2D matrix can be stored as a single dimension cell array. To access a particular row,column you can convert the subscript to linear index and then access it from the array. Example code can be like below:
MAT_cell = cell(1,7);
MAT_cell{1} = "e1'*e1";
MAT_cell{2} = "e2'*e2";
MAT_cell{3} = "e3'*e3";
MAT_cell{4} = "e4'*e4";
MAT_cell{5} = "e1'*e2";
MAT_cell{6} = "e2'*e3";
MAT_cell{7} = "e3'*e4";
matSize = [4 2];
% The index (3,2) can be accessed like below:
linIndex = sub2ind(matSize,3,2);
val = MAT_cell(linIndex)
I hope this will help you.
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