Geodesics on an ellipsoid - Pittman's method
The direct and inverse problems of the geodesic on an ellipsoid are fundamental geodetic operations. This paper presents a detailed derivation of a set of recurrence relationships that can be used to obtain solutions to the direct and inverse problems with sub-millimetre accuracies for any length of line anywhere on an ellipsoid. These recurrence relationships were first described by Michael Pittman in 1986, but since then, little or nothing about them has appeared in the geodetic literature. This is unusual for such an elegant technique and it is hoped that this paper can redress this situation. Pittman's method has much to recommend it.