how to stop overwriting a matrix in a for loop in matlab

Question

Reinhardt RADING 2021-2-9

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/740632-how-to-stop-overwriting-a-matrix-in-a-for-loop-in-matlab

评论： Reinhardt RADING 2021-2-9

采纳的回答： KSSV

在 MATLAB Online 中打开

Hello all,

i'm stuck with this code.

I am trying to get the value of M.

M is the product of three matrices, iterated and multiplied 100 times. please see below.

    for n  =1:100
        y = OUT.lin.matin(:,:,n);               %gets valiue from a stored array
        %y is a unitary matrix
           x = OUT.lin.db0(n);                      %gets valiue from a stored array
          % x is a scalar
        w =[exp(1i*x),exp(1i*-x)];        % creating the exponential 
     
        k = diag(w);                                     % creating a diagonal matrix of W
        M = y*k*y'; 
end

I think M overrides each iteration, but i would like to get the results from the 100 iterations. Kindly assist.

Thanks in advance.

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Answer 1

KSSV 2021-2-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/740632-how-to-stop-overwriting-a-matrix-in-a-for-loop-in-matlab#answer_619092

在 MATLAB Online 中打开

M = zeros([],[],100) ; % give exact row and column size 
    for n  =1:100
        y = OUT.lin.matin(:,:,n);               %gets valiue from a stored array
        %y is a unitary matrix
           x = OUT.lin.db0(n);                      %gets valiue from a stored array
          % x is a scalar
        w =[exp(1i*x),exp(1i*-x)];        % creating the exponential 
     
        k = diag(w);                                     % creating a diagonal matrix of W
        M(:,:,n) = y*k*y'; 
end