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shayanjm/reverse-haversine.clj

Created March 23, 2015 17:25
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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.
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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}))
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