_prim(A);
% This command means we can't run the demo, so it's commented out.

%%
% Oops, travel time isn't symmetric!  Let's just pick the longest possible
% time.
A = max(A,A');
T = mst_prim(A);
sum(sum(T))/2 % total travel time in tree

%% 
% Well, the total weight isn't that helpful, let's _look_ at the data
% instead.
clf;
gplot(T,xy);

%%
% Hey!  That looks like the US!  You can see regional airports and get some
% sense of the overall connectivity.  

%% Connected components
% The connected components