Assembling two matrices into one in a given pattern

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Dario Garic 2021-1-20

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https://ww2.mathworks.cn/matlabcentral/answers/722049-assembling-two-matrices-into-one-in-a-given-pattern

评论： Jan 2021-1-20

Hello everbody,

I am fairly new to Matlab and I have some difficulties solving a task from university.

The task ist to assemble two matrices into one global matrices in such form:

A = [ 1 2; 1 2 ]
B = [2 3; 2 3] 
% Assemble A and B into C
C = [1 2 0; 1 4 3; 0 2 3]

I tried it using a for loop but I can't manage to insert them into the given form in C.

When searching for a solution I came across "indexing" but I couldn't figure out how to use it in my problem.

I am grateful for any and all help!

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Dario Garic 2021-1-20

编辑：Dario Garic 2021-1-20

Hello Jan, thanks for your time!

I can assemble the matrix any way I want, as long as it works.

Yes you are right, I didn't explain the problem efficient enough, sorry!

I have n matrices in the form 2 x 2. I need to assemble those (Matrix A and B) into a global matrix C with the form n+1 x n+1.

For example:

I have n = 2. That means I have to allocate two 2 x 2 matrices into a global matrix 3 x 3.

I know that there is the function blkdiag, but there is a catch to the task. The number from A (2,2) needs to be added with the number in B(1,1) in the global matrix C.

The code should work for any number n.

Does this descripton help?

Jan 2021-1-20

See my edited answer.

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Answer 1

Jan 2021-1-20

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/722049-assembling-two-matrices-into-one-in-a-given-pattern#answer_602059

编辑：Jan 2021-1-20

A bold guess (although a wrong guess might be more confusing than posting nothing):

A = [1 2; 1 2];
B = [2 3; 2 3];
[s1, s2]      = size(A);
C             = zeros([s1, s2] + 1);
C(1:s1, 1:s2) = A;
C(2:s1+1, 2:s2+1) = C(2:s1+1, 2:s2+1) + B;

[EDITED after your comment]

List = {[1 2; 1 2], [2 3; 2 3], [4 7; 8 9]};
n = numel(List);
C = zeros(n + 1, n + 1);
for k = 1:n
    C(k:k+1, k:k+1) = C(k:k+1, k:k+1) + List{k};
end