  The software tool GRworkbench is an ongoing project in visual, numerical
General Relativity at The Australian National University. Recently, the
numerical differential geometric engine of GRworkbench has been rewritten using
functional programming techniques. By allowing functions to be directly
represented as program variables in C++ code, the functional framework enables
the mathematical formalism of Differential Geometry to be more closely
reflected in GRworkbench . The powerful technique of `automatic
differentiation' has replaced numerical differentiation of the metric
components, resulting in more accurate derivatives and an order-of-magnitude
performance increase for operations relying on differentiation.
