Implementation of the reverse of Haversine formula. Takes one set of latitude/longitude as a start point, a bearing, and a distance, and returns the resultant lat/long pair.

reverse-haversine.clj

(defn reverse-haversine
  "Implementation of the reverse of Haversine formula. Takes one set of latitude/longitude as a start point, a bearing, and a distance, and returns the resultant lat/long pair."
  [{lon :long lat :lat bearing :bearing distance :distance}]
  (let [R 6378.137 ; Radius of Earth in km
        lat1 (Math/toRadians lat)
        lon1 (Math/toRadians lon)
        angdist (/ distance R)
        theta (Math/toRadians bearing)
        lat2 (Math/toDegrees (Math/asin (+ (* (Math/sin lat1) (Math/cos angdist)) (* (Math/cos lat1) (Math/sin angdist) (Math/cos theta)))))
        lon2 (Math/toDegrees (+ lon1 (Math/atan2 (* (Math/sin theta) (Math/sin angdist) (Math/cos lat1)) (- (Math/cos angdist) (* (Math/sin lat1) (Math/sin lat2))))))]
    {:lat lat2 :lon lon2}))