Summing squared elements of a column of a matrix

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kevin cecere palazzo 2019-8-6

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https://ww2.mathworks.cn/matlabcentral/answers/475128-summing-squared-elements-of-a-column-of-a-matrix

回答： Star Strider 2019-8-6

for i=1:N
s(i)=sum(V(:,2))/sqrt(n);
t(i)=sum(V(:,2))/sqrt(sum((V(:,i).*V(:,i)));
end

Both s and t are Nx1 vectors, while V is a nxN matrix. In s I summed the elements of each column of V for every element of s. How can I divide, in t, by the square root of the sum of the SQUARED elements of each column of V?

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Answer 1

Star Strider 2019-8-6

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https://ww2.mathworks.cn/matlabcentral/answers/475128-summing-squared-elements-of-a-column-of-a-matrix#answer_386476

在 MATLAB Online 中打开

It’s not clear what you want to do.

Try this:

V = rand(6,5);                                          % Guess What ‘V’ Is
n = size(V,1);
N = size(V,2);
s = sum(V)/sqrt(n);                                     % Sum Over Columns, Divide By ‘sqrt(n)’
t = sum(V)./sqrt(sum(V.^2,2));                          % Sum Over Columns, Divide By ‘sum(sqrt(Rows))’