Cost function

Introduction

The cost function can be simple: for instance, it can be defined as the length of a line. The cost function can also be more elaborate and take into account not only length of the lines but also their capacity, maximum transmission (travel) rate and other line characteristics, for instance to obtain a reasonable approximation of travel time. There can even be cases in which the nodes visited add to the cost of the path as well. These may be called turning costs, which are defined in a separate turning-cost table for each node, indicating the cost of turning at the node when entering from one line and continuing on another. This is illustrated in Figure below.

Figure: Network neighbourhood of node N with associated turning costs at N. Turning at N onto c is prohibited because of its direction, so no costs are mentioned for turning onto c. A turning cost of infinity () also means that the turn is prohibited.

 

Learning outcomes

Prior knowledge

Outgoing relations

Incoming relations