How to efficiently calculate a weighted sum of 3 dimensional matrix through a vector in matlab

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Hancheng Zhu 2023-11-17

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https://ww2.mathworks.cn/matlabcentral/answers/2048577-how-to-efficiently-calculate-a-weighted-sum-of-3-dimensional-matrix-through-a-vector-in-matlab

评论： Matt J 2023-11-20

采纳的回答： Bruno Luong

A is a 3 dimensional matrix (M*N*K), b is a vector with length K. I need to calculate

, which is a 2 dimensional matrix (M*N). But i don't want to write it by a explicit summation because it is too slow. Is there any way to calculate it efficiently through matlab? Please attach the code if convenience.

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Hancheng Zhu 2023-11-20

Your code is very good and concise, bro. But it spends more time than the latter answer below. Thanks for your kindly help.

Matt J 2023-11-20

@Hancheng Zhu If that means you've settled on one of the answers below, please Accept-click one of them.

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Bruno Luong 2023-11-17

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编辑：Bruno Luong 2023-11-17

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This uses matrix multiplication so it should be well optimized and fast.

[m,n] = size(A, [1 2]);
C = reshape(A,m*n, []) * B(:);
C = reshape(C, m, n);

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MATLAB Language Fundamentals Matrices and Arrays Matrix Indexing

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