Performing Iteration for a Matrix

Question

MarshallSc 2022-2-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1658065-performing-iteration-for-a-matrix

编辑： Torsten 2022-2-25

I want to perform an iterative operation on each element of a matrix according to this equation which is for a 3 x 3 matrix:

For example, by having this matrix:

a = [0 0.2 -0.6; -0.2 0 0.4; 0.6 -0.4 0]
a = 3×3
         0    0.2000   -0.6000
   -0.2000         0    0.4000
    0.6000   -0.4000         0

I wrote the code for the first iteration for each element seperately but my original matrix is 1000 x 1000, so I need a code that can do this operation for the whole matrix. The code that I wrote for each element of the matrix is:

a_1(1,2) = a(1,2) + (0.25 * (a(1,3) + a(3,2))); %CF is 0.25
a_1(1,3) = a(1,3) + (0.25 * (a(1,2) + a(2,3)));
a_1(2,1) = a(2,1) + (0.25 * (a(2,3) + a(3,1)));
a_1(2,3) = a(2,3) + (0.25 * (a(2,1) + a(1,3)));
a_1(3,1) = a(3,1) + (0.25 * (a(3,2) + a(2,1)));
a_1(3,2) = a(3,2) + (0.25 * (a(3,1) + a(1,2)))
a_1 = 3×3
         0   -0.0500   -0.4500
    0.0500         0    0.2000
    0.4500   -0.2000         0

Which will give the result as shown above. The term that starts with CF on the RH is essentially saying no index is chosen twice in the same place. I'd appreciate it if someone can please help me. Thank you!

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Torsten 2022-2-25

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1658065-performing-iteration-for-a-matrix#answer_904075

编辑：Torsten 2022-2-25

在 MATLAB Online 中打开

L = 2;
CF = 0.25;
a = [0 0.2 -0.6; -0.2 0 0.4; 0.6 -0.4 0];
n = size(a,1);
A = zeros(L,n,n);
A(1,:,:) = a;
for l = 2:L
    for i = 1:n    
        for j = 1:n
            A(l,i,j) = A(l-1,i,j) - CF*(A(l-1,i,i) + 2*A(l-1,i,j) + A(l-1,j,j));
            for k = 1:n
                A(l,i,j) = A(l,i,j) + CF*(A(l-1,i,k) + A(l-1,k,j));
            end
        end
    end
end