public HashSet<BetterPoint> between(double rmin, double rmax)
    {
        HashSet<BetterPoint> result = new HashSet<BetterPoint>();
        BetterPoint pointI = null;

        Iterator<BetterPoint> i = this.iterator();
        while(i.hasNext())
        {
            pointI = i.next();
            if(pointI.distance() <= rmax && pointI.distance() >= rmin)
                result.add(pointI);
        }

        return result;
    }