How to multiply matrix with vector?

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Lu Da Silva 2021-3-26

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https://ww2.mathworks.cn/matlabcentral/answers/784291-how-to-multiply-matrix-with-vector

评论： Lu Da Silva 2021-3-26

I need to find E and K as 2 separate vectors.

A, B and D are matrices of their own (3x3). N and M are vectors (2x5).

Mathematically E = A*N + B*M and K = B*N + D*M but I struggle to implement it into MatLab, especially with the fact that it's an inverse matrix... I'd appreciate any help!

Thank you in advance :)

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Answer 1

Jan 2021-3-26

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https://ww2.mathworks.cn/matlabcentral/answers/784291-how-to-multiply-matrix-with-vector#answer_659036

N and M are vectors (2x5)
A, B and D are matrices of their own (3x3)

Then the equation [E;K] = [A, B; B, D]^-1 * [N;M] is not mathematically defined. The inverse of a 6x6 matrix is 6x6. You cannot multiply this with a 4x5 matrix.

Actually Matlab was devolopped for exactly such Matrix equations. So using the \ operator will do everything you need already - if the problem has a solution. But this is not the case for your problem.