Log in as user ads. At the first prompt type loran. At the second prompt type ldx. When you've finished, type bye.
Another interesting package is GMT (generic mapping tools). These programs calculate map projections, and much else besides. They are very well documented and available free of charge for down-loading, as a compressed tar file. GMT was developed by Pål Wessel and Walter H.F. Smith of the University of Hawaii. Much less comprehensive is my humble offering:
For conversion in both directions between lat-lon and x-y according to the Ordnance Survey projection, which is Transverse Mercator centred on 2°W. with a scale factor applied on the central meridian, you can use a set of coordinate conversion programs written by me and available as C source. (``A poor thing, sir, but mine own.'')