How to Add a row vector to a column vector like matrix multiplication

Question

I have a nx1 vector and a 1xn vector. I want to add them in a special manner like matrix multiplication in an efficient manner (vectorized):

Example:

Answer 1

You can use the repmat function (replicate matrices):

repmat(A,1,3)+repmat(B,3,1)

Answer 2

From R2016b you can simply do:

A=[1 2 3]'

B=[4 5 6]

A+B

ans =

     5     6     7
     6     7     8
     7     8     9

Matlab will silently expand both vectors and do the element wise sum. This feature has not been without it's controversy. You can check the details here:

Matlab expands arithmetic

Answer 3

You can use bsxfun:

A=[1 2 3]'

B=[4 5 6]

bsxfun(@plus, A, B)

The result is

ans =

     5     6     7
     6     7     8
     7     8     9