How to sum the results of a loop?

 I need to sum the values of D and put the result in a single variable...
How can I do this?

   x=[1 2 3 4 5];

d= [0 10 20 30 40;
    10 0 50 60 70;
    20 50 0 80 90;
    30 60 80 0 100;
    40 70 90 100 0]; 

for i=1:length(x)-1
    j=i+1;
    D=d(x(1,i),x(1,j))
end

>> test

D =

      10

D =

      50

D =

      80

D =

     100

Answer 1

[James Tursa]

E.g., for generic x

s = sub2ind(size(d),x(1:end-1),x(2:end));
Dsum = sum(d(s));

If you always wanted to sum the super-diagonal, then

Dsum = sum(diag(d,1));