Find the distance in KM from 2 geo points

painless-distance-from-geopoint.java

double deg2rad(def deg) {
  return deg * (Math.PI/180)
}

double getDistanceFromLatLonInKm(def lat1,def lon1,def lat2,def lon2) {
  def R = 6371; // Radius of the earth in km
  def dLat = deg2rad(lat2-lat1);  // deg2rad below
  def dLon = deg2rad(lon2-lon1); 
  def a = 
    Math.sin(dLat/2) * Math.sin(dLat/2) +
    Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * 
    Math.sin(dLon/2) * Math.sin(dLon/2)
    ; 
  def c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
  def d = R * c; // Distance in km
  return d;
}

return getDistanceFromLatLonInKm(-27.3942144,153.1196363,-37.6690123,144.8388333);