confusing regarding two cases of multiplication in MATLAB?

I know that in MATLAB,we use ".*" and"*" for multiplication of matrices

But when one should use only "*" and when one should also use dot with asterik ".*" ??

Please kindly explain with examples

Especially if one operand is a scalar or 1X1 matrix and 2nd matrix is a row vector or column vector? In that case ,only asterik"*" will be sufficent?

Answer 1

[Jesus Sanchez]

".*" -> Element-wise multiplication

Example:

[1 2 3].*[1 2 3] = [1*1 2*2 3*3] = [1 4 9]

"*" -> Matrix multiplication

Example:

[1 2 3]*[1 2 3].' = [1*1 +2*2 +3*3] = [1+4+9] = [14]

[ABTJ]

what if one operand is a scalar or 1X1 matrix and 2nd matrix is a row vector or column vector? In that case ,only asterik will be sufficent?

[Image Analyst]

In the case where one variable is a scalar, either * or .* would work, though I, and I expect most other people, use only * (without the unneeded dot).

Answer 2

[Steven Lord]

See this documentation page for a discussion of the difference between array operations and matrix operations, including examples showing what each does.