Understanding the difference between normal multiplication between two vectors and multiplication with dot operator.

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chaaru datta 2023-10-20

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https://ww2.mathworks.cn/matlabcentral/answers/2036141-understanding-the-difference-between-normal-multiplication-between-two-vectors-and-multiplication-wi

编辑： Stephen23 2023-10-20

Hello all, I am trying to understood the difference between normal multiplication and mutliplication with dot operator in caseof two vectors.

For example,

If we have two vector H of dimension 2 X 4 and B of dimension 4 X 1 then writing

Y = H*B % ---(1)

do not cause any error.

But if we write

Y = H.*B %--- (2)

then it gives the following error: Arrays have incompatible sizes for this operation.

Any help is highly appreciated.

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Walter Roberson 2023-10-20

MATLAB does not have any dot operator. MATLAB has a series of operators whos representation involves two characters, the first of which happens to be a dot.

So in A.*B that is not parsed as A followed by an operator '.' followed by an operator '*' followed by B: it is parsed as A followed by a single operator designated by '.*' followed by B.

This is similar to the way that A>=B is not parsed as A followed by a > operator then a = operator then B, but is instead A followed by a single operator designed by '>=' followed by B

chaaru datta 2023-10-20