[pgrouting-users] Different results - pgr_dijkstra/pgr_kdijkstrapath/cost/pgr_ksp

[Stephen Woodbridge]

On 3/25/2014 10:45 AM, Omar Fernando Pessôa wrote:
> I have a city roads data base witch is returning different values from
> this 'selects'.
>
>     select sum(cost) from pgr_Dijkstra('SELECT id, source, target, cost,
>     reverse_cost FROM ruas',3423, 3839, true, true);
>
>     select sum(cost) from pgr_kdijkstraPath('SELECT id, source, target,
>     cost, reverse_cost FROM ruas',3423, array[3839], true, true);
>
>     select sum(cost) from pgr_ksp('SELECT id, source, target, cost,
>     reverse_cost FROM ruas', 3423, 3839, 1, true);
>
>
> Manually I have seen that the pgr_Dijkstra has the correct path.
>
> And the others has passed from edges who is not the shortest path.
>
> Is it an alghorithm error?

Omar,

It would seem that these all should return the same basic result, or at 
least a result where the total cost is the same in all cases.

I know there were some fixes made at some point to correct a problem of 
multiple parallel paths where a non-short path was getting returned. It 
is possible that this fix may need to be applied to these other 
algorithms also.

Please open a ticket and if possible add a simple example that 
reproduces the problem.

If you can did into the code, we would be happy to get a pull request 
against the "develop" branch.

Thank you,
   -Steve