Preallocating an array or a vector in matlab before a for loop

Question

A Poyser 2023-2-15

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1912920-preallocating-an-array-or-a-vector-in-matlab-before-a-for-loop

评论： A Poyser 2023-2-15

I have several variables that I want to preallocate in my code before my for loop. I was hoping someone could show me the correct way to write this preaalocation. Currently it looks like this but it is giving me errors

k = 1:24; 
sigma_infty = zeros(length(:,k));
eps_infty = zeros(length(:,k));
for k = k
    %
    sigma_infty(:,k) = [10*k 0 0 0 0 0]';
    %
    eps_infty(:,k) = S2*sigma_infty(:,k);
end

I keep getting told that I length and/or zeros is an unregognised function and I am unsure how to write the corrct preallocation.

Could someone please clarify how to correctly allocate these variable for me?

Thanks

Alex

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Answer 1

KSSV 2023-2-15

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1912920-preallocating-an-array-or-a-vector-in-matlab-before-a-for-loop#answer_1172100

在 MATLAB Online 中打开

N = 24 ; 
sigma_infty = zeros(6,N);
eps_infty = zeros(6,N);
for k = 1:N
    %
    sigma_infty(:,k) = [10*k 0 0 0 0 0]';
    %
    eps_infty(:,k) = S2*sigma_infty(:,k);
end