Haversine algorithmus

file1.groovy

    double EARTH_RADIUS = 6371
    /**
     * Calculate distance based on Haversine algorithmus
     * (thanks to http://www.movable-type.co.uk/scripts/latlong.html)
     *
     * @param latitudeFrom
     * @param longitudeFrom
     * @param latitudeTo
     * @param longitudeTo
     * @return distance in Kilometers
     */
    BigDecimal calculateDistance(BigDecimal latitudeFrom, BigDecimal longitudeFrom,
                                 BigDecimal latitudeTo, BigDecimal longitudeTo) {

        def dLat = Math.toRadians(latitudeFrom - latitudeTo)
        def dLon = Math.toRadians(longitudeFrom - longitudeTo)

        //a = sin²(Δlat/2) + cos(lat1).cos(lat2).sin²(Δlong/2)
        //distance = 2.EARTH_RADIUS.atan2(√a, √(1−a))
        def a = Math.pow(Math.sin(dLat / 2), 2) +
                Math.cos(Math.toRadians(latitudeFrom)) *
                Math.cos(Math.toRadians(latitudeTo)) * Math.pow(Math.sin(dLon / 2), 2)
        return 2 * EARTH_RADIUS * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))

    }