Hello All,<br><br>      I have a question about defining A* heuristic. I am trying to implement an algorithm in a paper using BGL. Here authors have used A* Dijkstra&#39;s to calculate shortest route with an additional constraint of route length should be no longer than a threshold value t. <br>
<br>I think due to this threshold constraint they are using A* instead of normal Dijkstra&#39;s algorithm.<br><br>I came to know A* is already there in Boost Graph Library. I just have a basic knowledge about A* algorithm that it finds the shortest route based on the  heuristic H. <br>
<br>I tried to look into the example in BGL, but I did not get any hint to define a heuristic. Can anybody give me some hints or some useful links of how can I define a heuristic for this particular scenario of finding the shortest path between nodes that is no longer than threshold t through A* Dijkstra. This would be really helpful for me to proceed further.<br clear="all">
<br>-- <br>Regards,<br>Giridhar<br>