A Common lisp library to solve direct and inverse geodesic problem. It implements Charles Karney’s method from this paper: https://doi.org/10.1007/s00190-012-0578-z
;; Two examples from the paper
(geodesic:direct (geodesic:radians 40) (geodesic:radians 30) 1e7)
-> 0.7294308683855781d0
-> 2.405847362846288d0
-> 2.6021143369561823d0
(geodesic:inverse (geodesic:radians -30) (geodesic:radians 29.9) (geodesic:radians 179.8))
-> 1.9989832879260477d7
-> 0.3160648483358468d0
-> 2.825854840938509d0