graphdb/src/main/java/com/orientechnologies/orient/graph/sql/functions/OSQLFunctionHeuristicPathFinderAbstract.java
public double gcdist(double lata, double longa, double latb, double longb) {
        double midlat, psi, dist;
        midlat = 0.5 * (lata + latb);
        psi = 0.0174532925
                * Math.sqrt(Math.pow(lata - latb, 2)
                + Math.pow((longa - longb)
                * Math.cos(0.0174532925 * midlat), 2));
        dist = 6372.640112 * psi;
        return dist;
    }
public double gcdist(double lata, double longa, double latb, double longb) {
        double midlat, psi, dist;
        midlat = 0.5 * (lata + latb);
        psi = 0.0174532925
                * Math.sqrt(Math.pow(lata - latb, 2)
                + Math.pow((longa - longb)
                * Math.cos(0.0174532925 * midlat), 2));
        dist = 6372.640112 * psi;
        return dist;
    }
obtains from https://github.com/enderceylan/CS-314--Data-Structures/blob/master/HW10-Graph.java