Tools for analyzing intersecting tracks: The x2sys package

I present a new set of tools for detection of intersections among tracks in 2-D Cartesian or geographic coordinates. These tools allow for evaluation of crossover errors at intersections, analysis of such crossover errors to determine appropriate linear models of systematic corrections for each track, and application of these corrections and further adjustments to data that completely eliminates crossover discrepancies from final 2-D data compilations. Unlike my older x_system tools, the new x2sys tools implement modern algorithms for detecting track intersections and are capable of reading a wide range of data file formats, including data files following the netCDF COARDS convention. The x2sys package contains several programs that address the various tasks needed to undertake a comprehensive crossover analysis and is distributed as a supplement to the Generic Mapping Tools, making them available for all computer platforms and architectures.