compute sums by accumulating in a for-loop

Question

Kyle 2023-12-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2055719-compute-sums-by-accumulating-in-a-for-loop

评论： Kyle 2023-12-3

I am trying to accumulate sums (phi(l) for lags " l"in a for loop given the code below. I keep getting "Unable to perform assignment because the left and right sides have a different number of elements." I have tried multiple ways to try and fix it but nothing is working.

x=normrnd(0,1,100,1);
xprime=detrend(x,'constant');
phi=zeros(14,1);
L= [0:13]';
for l=1:14
    phi(l)=(sum(xprime(1:100-l)).*xprime(1+l:100)/(100-(l-1)-1));
end  
Unable to perform assignment because the left and right sides have a different number of elements.

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Answer 1

Image Analyst 2023-12-3

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2055719-compute-sums-by-accumulating-in-a-for-loop#answer_1364769

在 MATLAB Online 中打开

Look at this:

x=normrnd(0,1,100,1);
xprime=detrend(x,'constant');
phi=zeros(14,1);
L= [0:13]';
for l=1:14
    temp = (sum(xprime(1:100-l)).*xprime(1+l:100)/(100-(l-1)-1))
    fprintf('The size of temp = %d.\n', numel(temp))
    phi(l)=(sum(xprime(1:100-l)).*xprime(1+l:100)/(100-(l-1)-1));
end  
temp = 99×1
    0.0116
    0.0105
    0.0110
    0.0077
   -0.0046
   -0.0012
   -0.0141
    0.0183
    0.0027
   -0.0052
The size of temp = 99.
Unable to perform assignment because the left and right sides have a different number of elements.

So you're trying to stuff 99 values into a slot meant for only one value, phi(l). Not sure how to fix it because I'm not sure what your intent is. Did you mean for phi to be a 99 by 14 matrix and you want to put temp into the columns of phi?