A three-dimensional ray-tracing computer program (digest of ESSA technical report, ITSA no. 17)

ESSA Technical Report, IER-17/ITSA-17 (Jones, 1966), is the documentation of an accurate, versatile computer program which computes ray paths through a medium whose index of refraction varies in three dimensions. The program is written in CDC 3600 FORTRAN, which is similar to IBM FORTRAN IV. The program was developed to trace radio rays through the ionosphere, but could be converted to other applications by substituting an appropriate index-of-refraction subroutine.