code: public double dist(int k, Vec x, List<Double> qi)
      {
          return points.get(k).dist(x, qi);
      }
docs: Computes the Euclidean distance in the kernel space between the
  {@code k}'th KernelPoint and the given vector
  @param k the index of the KernelPoint in this set to contribute to the
  dot product
  @param x the point to get the Euclidean distance to
  @param qi the query information for the vector, or {@code null} only if
  the kernel in use does not support acceleration.
  @return the Euclidean distance between the {@code k}'th KernelPoint and
  {@code x} in the kernel space