Some tactical algorithms for spherical geometry

This report presents two great circle navigation algorithms, a closest point of approach algorithm and intercept algorithm. It also presents an implementation program for the algorithms that is written in the BASIC language for an IBM PC. Instead of using classical spherical geometry or the general spherical triangle, these algorithms incorporate rectangular coordinates and vectors on the surface of the spherical. The intent of the report is to provide algorithms for spherical earth models that can be used for situations in which flat earth models are not appropriate, but that do not require the sophistication of rotating earth models. (Author) ; Approved for public release; distribution is unlimited. ; Prepared for: Director of Tactical Readiness Division Office of the Chief of Naval Operations Department of the Navy ; http://archive.org/details/sometacticalalgo00shud