easy beginner question : how to sum up

I think this i quite easy for you guys - but ive not found an answer yet (perhaps because my english skills are limitated) I want to summ up two vektors like this V1 = [1 2 3] V2 = V1' (the transposed vektor) and I want to get the ?inner? sum

   1 2 3
  1
  2
  3

so that i get a matrix with this relsult ( so just row plus column )

2 3 4
3 4 5
4 5 6

would be really nice if you can help me. thx a lot

[John D'Errico]

You called this an inner sum. But really, the correct term would be a generalized outer product.

https://en.wikipedia.org/wiki/Outer_product

[James Tursa]

OP is summing, not multiplying. I.e., an "outer sum" not an "outer product"

Answer 1

[Star Strider]

Use the bsxfun function with the @plus function:

A = [1 2 3];
B = bsxfun(@plus, A(:), A)

B =
     2     3     4
     3     4     5
     4     5     6

(In R2017a, this implicit expansion is done automatically. I still prefer bsxfun because it will throw an error if I do something wrong.)

[Sean de Wolski]

How would bsxfun throw an error that implicit expansion won't?

[Star Strider]

I’ve not tried implicit expansion without bsxfun. I’m in no rush to do so.

Answer 2

[Guillaume]

If you're using R2016b or later, simply

V1 + V1.'

In earlier versions

bsxfun(@plus, V1, V1.')

Answer 3

[Paul Hoffmann]

thx for the answer - helped a lot !