Sum (rendezvous equation) in matlab

I want to write the below equation(rendezvous) in matlab, i belongs to {1,2,…,7} , write a for loop for i and a switch for j, but I don’t know how to write the sum properly, will you help

Answer 1

[Andrei Bobrov]

out = sum(bsxfun(@minus,x(:),x(:)'),2);