Then you know also the answers to your questions. :), perhaps without
realising that.
Yes, it does keep track of already determined costs/routes during routing.
The problem is, the classical A* has enormous memory demand for long
routes, growing quadratically with the route distance.
That is why BRouter comes in the 2nd step with the cut off feature. But you
need an estimation of optimal route cost by fast draft run( typically I
guess 20% of time of the 2nd run ) , that is very near to optimal route.
It need not to remember the route found at the first pass, all what is
needed is its cost.
What at the 2nd pass the sum of partial cost and remaining distance is
bigger than 1st pass cost, the partial route is thrown away.
If it were 1 pass only, you would have no idea
if the partial route still can be the optimal route or not and you would
have to keep many more routes and points.
The cutting off of bad routes progressively increases its rate, while the
routing approaches the destination, when A* would have been at the top of
its resource hunger.
Dne 16. března 2020 18:57:52 Harry van der Wolf <[email protected]> napsal:
Thanks, but that theorectical description I already knew :)
I mean: does it keep some matrix in memory with the already determined
costs/routes?
And if it finds a better route in the 2nd step, then based on what? Because
it will not be available after the first run. And why is that first step
then necessary?
etcetera, etcetera.
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