MATLAB: Afficient way to create “sum matrix”

Question

Hi,

So i would like to implement a function that get a vector as input lets :

g=[g1, g2, g3]

and return a matrix that contain a sum of pairs: so for g , the output matrix G contain 9 elements the G(i,j)=g(i)+g(j)

The problem is that g will be very large vector.

Does anyone know an efficient way to do that with sparse matrices

Thanks

Answer 1

g = 1:3;
m = g+g(:)
m = 3×3
     2     3     4
     3     4     5
     4     5     6