code: public static int medoid(boolean parallel, Collection<Integer> indecies, List<? extends Vec> X, DistanceMetric dm, List<Double> accel)
      {
          return medoid(parallel, indecies, 1.0/indecies.size(), X, dm, accel);
      }
docs: Computes the medoid of a sub-set of data
  @param parallel whether or not the computation should be done using multiple cores
  @param indecies the indexes of the points to get the medoid of
  @param X the list of all data
  @param dm the distance metric to get the medoid with respect to
  @param accel the acceleration cache for the distance metric
  @return the index value contained within indecies that is the medoid