[postgis-devel] Having problems under standing the distance matrix of TSP in respect to route network pgroute version 2

[Dave Potts]

In the travel sales person problem an example is provided,  I having 
problems understanding it

The example route network is posted as 
http://docs.pgrouting.org/dev/doc/src/developer/sampledata.html#sampledata

I have assume the distance between red node 1 and red node 3 is 2, ie 
the unit distance 1 +1  which I  make to be 2

given that

I think the route matrix should be

     1 2 3 4
======
1 | 0 1 2 3
2 | 1 0 1 2
3 | 2 1 0 1
4 | 3 2 1 0

distance 1 to 4 is 1+1 +1 ==3
distance 2 to 4 is 1+1       ==2
distance 3 to 4 is 1
etc

But the give value is (please see 
http://docs.pgrouting.org/dev/src/tsp/doc/index.html)
     1 2 3 4

1  {0,1,2,3},
2  {1,0,3,2},
3  {2,3,0,4},
4  {3,2,4,0}

I just don't understand how the distance between 3 and 4 can be the value 4, ditto he values between 2 and 3

Have I missed something sly ?

Dave.