Proj and invproj perform respective forward and inverse transformation of cartographic data to or from cartesian data with a wide range of selectable projection functions. Geod and invgeod perform geodesic (Great Circle) computations for determining latitude, longitude and back azimuth of a terminus point given a initial point latitude, longitude, azimuth and distance (direct) or the forward and back azimuths and distance between an initial and terminus point latitudes and longitudes (inverse).
