The TRACK module tracks a segmented path through a 3D toroidal plasma and finds the intersections with a set of magnetic flux surfaces.

The TRACK module has been in continuous use since the early 1980's, although it has experienced occasional revisions. The present version is written in Fortran 90/95, using features that are relatively easy to adapt to different Fortran compilers and to link to other languages.
In addition, the algorithms for stepping along a line segment and finding intersections and tangencies have been extensively reworked in the present version for greater clarity and computational efficiency. TRACK requires geometry information (conversions between Cartesian, cylindrical and magnetic flux coordinates) that must be obtained from an MHD equilibrium interface.
The 2D and 3D conversions for inverse coordinate representations that were included in the original version of TRACK have been moved to the AJAX module, and are called directly from TRACK. In addition, the module AJAX_XPLASMA maps the AJAX calls to the 2D MHD equilibrium interface routines in XPLASMA.