How can I creat a "for" that builds more than one matrix?

Basically, I need to creat a Space Truss Member Stiffness Matrix for Member Axes, and every single beam of the truss needs a Stiffness matrix. 'xbar' contain the number of beams in the space truss. The main objective is to get the number of matrix that I need to use the element finite method. But I don't know how to do this at Matlab. I try it earlier this way, but I got the "()-indexing must appear

last in an index

expression. " error.

for i = 1:xbar

rigidlocal(i) = zeros(xbar,xbar);

rigidlocal(i)(1,4) = -1;

rigidlocal(i)(4,1) = rigidlocal(1,4);

rigidlocal(i)(1,1) = 1;

rigidlocal(i)(4,4) = rigidlocal(1,1);

end

Answer 1

[Anurag Ojha]

Hi Santos

The "()-indexing must appear last in an index expression," occurs because MATLAB does not support indexing with parentheses. Instead, use curly braces {} to index into a cell array.

Here is how the updated code will look like:

xbar = 10; % Number of beams in the space truss

rigidlocal = cell(xbar, 1); % Initialize cell array to store stiffness matrices

for i = 1:xbar
    rigidlocal{i} = zeros(4); % Initialize a 4x4 matrix for each beam

    rigidlocal{i}(1, 4) = -1;
    rigidlocal{i}(4, 1) = rigidlocal{i}(1, 4);
    rigidlocal{i}(1, 1) = 1;
    rigidlocal{i}(4, 4) = rigidlocal{i}(1, 1);

    % Display the matrix
    fprintf('Stiffness matrix for beam %d:\n', i);
    disp(rigidlocal{i});
end

Stiffness matrix for beam 1:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 2:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 3:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 4:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 5:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 6:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 7:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 8:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 9:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1

Stiffness matrix for beam 10:

     1     0     0    -1
     0     0     0     0
     0     0     0     0
    -1     0     0     1