How to connect logical operation using for loop?

I have 50 matrices of same dimension, in which some nonzero elements that are same among all matrices and some could have different values. Now i want to get the indices of constant elements and indices of variable elements. If there are only 2 matrices the problem would be solved easily by

cell = {} % cell matrix containing matrices
cell{1} = [1 2 0; 0 1 0; 5 0 0];
cell{2} = [1 3 0; 0 4 0; 5 0 6];
[row_constant,col_constant] = find(cell{1}==cell{2} & cell{1}~=0)

[row_var,col_var] = find(cell{1}~=cell{2} & cell{1}~=0 & cell{2}~=0)

I cant repeatedly write A==B & B==C & .... forever and the number of matrices are also not always the same.

What should i do ?

Answer 1

[Vishnu]

Hi @Jiahong Zou,

To solve the problem for an arbitrary number of matrices, you can use a loop in MATLAB. Here's an example code snippet that you can use:

% cell matrix containing matrices
cell{1} = [1 2 0; 0 1 0; 5 0 0];
cell{2} = [1 3 0; 0 4 0; 5 0 6];

num_matrices = numel(cell);  % Get the number of matrices

% Initialize variables to store the indices of constant and variable elements
[row_constant, col_constant] = find(cell{1} ~= 0);  % Start with non-zero elements of the first matrix
[row_var, col_var] = deal([]);  % Empty arrays

% Loop through the remaining matrices
for i = 2:num_matrices
    % Find the indices of constant elements
    [row, col] = find(cell{1} == cell{i} & cell{1} ~= 0)
    % Update the indices of constant elements
    [row_constant, col_constant] = intersect(row_constant, row, 'rows', 'stable')
    
    % Find the indices of variable elements
    [row, col] = find(cell{1} ~= cell{i} & cell{1} ~= 0 & cell{i} ~= 0)
    % Update the indices of variable elements
    [row_var, col_var] = unique([row_var; row], 'rows', 'stable')
end

row = 2×1

1 3

col = 2×1

1 1

row_constant = 2×1

1 3

col_constant = 2×1

1 2

row = 2×1

1 2

col = 2×1

2 2

row_var = 2×1

1 2

col_var = 2×1

1 2