Geodesic routines implemented in C

Author

Charles F. F. Karney (karne.nosp@m.y@al.nosp@m.um.mi.nosp@m.t.ed.nosp@m.u)

Version

2.2

Date

2025-08-19

Abstract

This is a C implementation of the geodesic algorithms from GeographicLib. This is a self-contained library (requiring only the standard C math library) which makes it easy to do geodesic computations for an ellipsoid of revolution in a C program. It is incorporated into PROJ and many people might prefer to use these routines via PROJ.

This an implementation in C of the geodesic algorithms described in

• C. F. F. Karney, Algorithms for geodesics, J. Geodesy 87, 43–55 (2013); addenda.

Other links

• Library documentation (all versions): https://geographiclib.sourceforge.io/C
• Git repository: https://github.com/geographiclib/geographiclib-c Releases are tagged in git as, e.g., v1.52, v2.0, etc.
• Source distribution: https://sourceforge.net/projects/geographiclib/files/distrib-C
• GeographicLib: https://geographiclib.sourceforge.io
• The library has been implemented in a few other languages.

Contents

• Introduction to the geodesic problem
• Information for PROJ user
• Use as a standalone library
• Library documentation
• Change log