@Before
  public void init() {
    for (int i = 0; i < m; ++i) {
      final double[] position = new double[n];
      for (int d = 0; d < n; ++d) position[d] = rnd.nextDouble();

      final RealPoint realPoint = new RealPoint(position);
      final DoubleType sample = new DoubleType(rnd.nextDouble());

      realPointList.add(realPoint);
      sampleList.add(sample);
      realPointSampleList.add(realPoint, sample);
    }
  }