Symbolic computation for manipulation of hierarchical bond graphs

In this chapter we have shown how symbolic computation is more than simply the use of symbolic algebra computer packages. The essential feature of modelling with hierarchical bond graphs is that information is kept in a symbolic format which represents the structure of the system and is transformed and translated into the desired representations and languages when required. Many different programs are used to achieve the manipulation of hierarchical bond graphs but in most cases the calculations and manipulations are performed symbolically rather than numerically, thus ensuring that the loss of information at any stage is minimised. The use of hierarchical bond graphs allows for the reuse of many components and the creation of libraries of bond graph models of subsystems. This aids the translation from initial conceptual modelling into a detailed simulation or design model and would not be possible without the use of significant symbolic computation.