How do you write an objective function for a shortest path problem?

Can anyone help me with this please? Not sure how to write one.

I need to write a function sort of like this:

function z=fobj(u)
%%d-dimensional sphere function sum_j=1^d (u_j-1)^2. 
%  with a minimum at (1,1, ...., 1); 
z=sum((u-1).^2);
end

But I need one to solve a shortest path problem. I have 49 nodes and I want to minimize the distance taken to travel between 2 selected nodes. Can someone help me please? I'd really really appreciate it.

Answer 1

[Walter Roberson]

Your inputs to the objective function should be indices. Your objective function should use the indices to index the distance table.

sum( distances( sub2ind( size(distances), x(1:end-1), x(2:end) ) )