Index exceeds the number of array elements - Error message

Question

zen 2022-6-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1749940-index-exceeds-the-number-of-array-elements-error-message

评论： Voss 2022-6-30

So I am getting an error where I believe n1 is larger than the array after n becomes n = 3, which is giving the error in ma. Premise of the code is to take 1 2, 3 4 5, 6 7 8 9, etc. Pretty sure I have to change the length but not sure how to go about it. What should I do? Here is the code:

clear all
mdata = [1 2 3 4 5 6 7 8 9];
n1 = 1;
k = 1;
for n = 1:length(mdata)
    ma(n) = (1/(k + 1)) * sum(mdata(n1:n1 + k));
    n1 = ((n1 + k) + 1);
    k = k + 1;
    std_ma = std(mdata);
end

Error message:

Index exceeds the number of array elements (9).

Error in untitled22 (line 11)

ma(n) = (1/(k + 1)) * sum(mdata(n1:n1 + k));

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Answer 1

Voss 2022-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/1749940-index-exceeds-the-number-of-array-elements-error-message#answer_995840

在 MATLAB Online 中打开

Here's one way to determine the number of iterations required:

clear all
mdata = [1 2 3 4 5 6 7 8 9];
n1 = 1;
k = 1;
N = numel(mdata);
n_iter = find(cumsum(2:N) <= N,1,'last')
n_iter = 3
for n = 1:n_iter
    ma(n) = (1/(k + 1)) * sum(mdata(n1:n1 + k));
    n1 = ((n1 + k) + 1);
    k = k + 1;
    std_ma = std(mdata);
end
disp(ma)
    1.5000    4.0000    7.5000