Multiply each column of n-by-m matrix by respective constants in m-by-1 vector

Hi

I have an n-by-m matrix and an m-by-1 vector. I want to multiply each of the m columns in the matrix by a constant specified in my vector.

E.g. if I have a matrix A=[1,2;3,4;5,6] and a vector B=[0.5,2] I want to multiply all the elements in the first column of my matrix by 0.5 and alle the elements en the second column by 2. That is, I would like to get the result C=[0.5,4;1.5,8;2.5,12].

It can easily be done by a loop, but I would like to know if the is a faster way to do this. A built in functionality? Dot-multiply doesn't seem to do the trick :(

Thanks in advance!

- Jesper

Answer 1

[the cyclist]

C = bsxfun(@times,A,B);

Answer 2

[vlad ap]

This also works:

C = B.*A

[Les Beckham]

This is the right way to do this. Much simpler.

[Steven Lord]

This works now due to implicit expansion. It would not have worked when the question was first asked in 2012.

Answer 3

[Jesper]

Hi Cyclist

This was exactly what I needed ;)

Thanks!

- Jesper

[the cyclist]

Happy to help. For future reference, you might want to add a remark like this as a "comment" to an answer (like I did here), rather than as a separate "answer". On questions that have more activity than this one, it helps to keep things organized logically.