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Vectorial Product and Matrix Product

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Andrea Cesaro 2023-4-16

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评论： Andrea Cesaro 2023-4-17

I have A*vxr where:

A is a matrix 3x3

v a vector 3x1

r a vector 3x1

and * rapresents the matrix product and x the vectorial product.

The question is: should i do the vectorial or the matrix product first?

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Torsten 2023-4-16

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I don't know of a rule in this case like "multiplication comes before addition". So without brackets set, it's ambiguous, I think.

Venkatanarasimha Hegde 2023-4-16

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Can you please specify for what application you are using this multiplication

Andrea Cesaro 2023-4-16

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The application is robotics and the formula is:

the cyclist 2023-4-16

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The formula you have posted here makes the order of operations very clear.

I'm not sure how to answer your question, partly because I'm not sure which parts of the math formula correspond to what you chose to call A and v.

Do you have your MATLAB code where you calculate mu_i_i?

Torsten 2023-4-16

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I'm not sure how to answer your question, partly because I'm not sure which parts of the math formula correspond to what you chose to call A and v.

I think it's the last term in the first line.

Andrea Cesaro 2023-4-16

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Exactly

the cyclist 2023-4-16

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Aaah. I had not even seen that term, because I hadn't noticed that the image was not fully visible, and needed to be scrolled. The expression seems ambiguous as written.

This isn't really a MATLAB question, of course. Maybe the source discusses the notation and conventions?

Or maybe you could calculate for a special case where the value of mu_i_i is known, and see which method gives that known result?

Andrea Cesaro 2023-4-16

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No, I must calculate mu_i_i with this formula. It is a problem of notation and conventions.

Venkatanarasimha Hegde 2023-4-16

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I think this has to do with tensor algebra. You have to look into tensor multiplication. Rather than just getting into expression,I would recommend you to understand the derivation of that ( you will physically understand which term is physically multiplied to another term).