FEL: The field encapsulation library

This paper describes the Field Encapsulation Library (FEL), which provides a grid-independent application programmer's interface to gridded three-dimensional field data. The C++ implementation of FEL is described, stressing the way in which the class hierarchy hides the underlying grid structure in a way that allows visualization algorithms to be written in a completely grid-independent manner: Appropriately defined coordinate classes play an important role in providing this grid independence. High-performance point location routines for data access are described and performance rimes are provided.