producing n*n matrix as an string in a loop

Hi,

I want to used the following code put I donot know how to safe K as an n*n mtrix in each loop. because by using my code the code only use the last element of K. would you mind helping me with that?

for i=1:20
    for j=1:20
        for k=1:400
            C{k}=E(i,j)/(1-nu(i,j)*nu(i,j))*[1,nu(i,j),0;nu(i,j),1,0;0,0,0.5-0.5*nu(i,j)];  %plane stress nu and E are poisson's ratio and young's modulus
        end
    end
end
 
for i=1:400,              %element assembly
    [B,Jac]=B_func(i);    %jacodian function 
    Ke{i}=B'*C{i}*B*Jac*0.5;         %Ke is elemental stiffness matrix
    m=elem(i,:);        
    n=[2*m-1;2*m]; 
    K(n,n)=K(n,n)+Ke{i};                    %compute global stiffness matrix K
end

[Stephen23]

Nothing in the calculation of C{k} seems to depend on the innermost loop. Is that intentional? If not, then what should change with k ?

[talayeh tavangar]

I want to to make K as an string with 400 elements and each element be a n*n matrix

[Stephen23]

"I want to to make K as an string with 400 elements and each element be a n*n matrix"

Yes, your question already makes that clear.

In my previous comment I pointed out that nothing inside your nested loops depends on k, so at best you would just end up with 400 identical matrices (and even if you chage the loop nesting you would stilll get 400 identical matrices). I suspect that this is not intentional, but as you have not given any information on what should change with k it makes it rather challenging to understand what you are actually trying to achieve. Perhaps a simple example would be best.

[talayeh tavangar]

I see your point. butmu consern is in the second loop where K is calculated. I donot know how to calculated it as an n*n matrix

[Image Analyst]

For a 2-D matrix you're going to need two loops, not one. Or at least that's the simplest

for row = 1 : n
    for col = 1 : n
        K(row, col) = whatever....
    end
end

[talayeh tavangar]

thanks

but in my code Ke is an string which has 400 elements of 6*6 matrix so I want to creat another sting as K which has 400 elements

[Image Analyst]

Do you have a screenshot of a book or article that shows the formula in standard kind of mathematical notation?

Also, attach a .mat file with all the variables we'll need to run your code.

Please read this link before improving your post.