FEL: the Field Encapsulation Library

The 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 times are provided.