@Test
  public void testConstructor() {
    double[] da = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
    DoubleDataset a = new DoubleDataset(da);

    IndexIterator it = a.getIterator();
    for (int i = 0; it.hasNext(); i++) {
      assertEquals(i, a.getElementDoubleAbs(it.index), 1e-5 * i);
    }

    DoubleDataset b = new DoubleDataset(da, 3, 4);

    it = b.getIterator();
    for (int i = 0; it.hasNext(); i++) {
      assertEquals(i, b.getElementDoubleAbs(it.index), 1e-5 * i);
    }

    DoubleDataset c = new DoubleDataset(a.getSliceView(new int[] {1}, null, new int[] {2}));
    it = c.getIterator();
    for (int i = 0; it.hasNext(); i++) {
      assertEquals(2 * i + 1, c.getElementDoubleAbs(it.index), 1e-5 * i);
    }

    // test hashes
    a.hashCode();
    b.hashCode();
    c.hashCode();
  }
  @Test
  public void testCreators() {
    double dz = 0.5;
    DoubleDataset z = DoubleDataset.createFromObject(dz);
    assertEquals(0, z.getRank());
    assertEquals(1, z.getSize());
    assertEquals(dz, z.getElementDoubleAbs(0), 1e-14);

    double[] da = {0, 1, 2, 3, 4, 5};
    DoubleDataset a = DoubleDataset.createFromObject(da);
    assertEquals(1, a.getRank());
    assertEquals(6, a.getSize());
    assertEquals(6, a.getShape()[0]);
    IndexIterator it = a.getIterator();
    for (int i = 0; it.hasNext(); i++) {
      assertEquals(i, a.getElementDoubleAbs(it.index), 1e-15 * i);
    }

    double[][] db = {{0, 1, 2}, {3, 4, 5}};
    DoubleDataset b = DoubleDataset.createFromObject(db);
    assertEquals(2, b.getRank());
    assertEquals(6, b.getSize());
    assertEquals(2, b.getShape()[0]);
    assertEquals(3, b.getShape()[1]);
    it = b.getIterator();
    for (int i = 0; it.hasNext(); i++) {
      assertEquals(i, b.getElementDoubleAbs(it.index), 1e-15 * i);
    }

    double[][] dc = {{0, 1, 2, 3}, {4, 5, 6}};
    DoubleDataset c = DoubleDataset.createFromObject(dc);
    assertEquals(2, c.getRank());
    assertEquals(8, c.getSize());
    assertEquals(2, c.getShape()[0]);
    assertEquals(4, c.getShape()[1]);
    it = c.getIterator();
    for (int i = 0; it.hasNext(); i++) {
      if (i < 7) assertEquals(i, c.getElementDoubleAbs(it.index), 1e-15 * i);
      else assertEquals(0, c.getElementDoubleAbs(it.index), 1e-15);
    }

    double[][] dd = {{0, 1, 2}, {4, 5, 6, 7}};
    DoubleDataset d = DoubleDataset.createFromObject(dd);
    assertEquals(2, d.getRank());
    assertEquals(8, d.getSize());
    assertEquals(2, d.getShape()[0]);
    assertEquals(4, d.getShape()[1]);
    it = d.getIterator();
    for (int i = 0; it.hasNext(); i++) {
      if (i != 3) assertEquals(i, d.getElementDoubleAbs(it.index), 1e-15 * i);
      else assertEquals(0, d.getElementDoubleAbs(it.index), 1e-15);
    }
  }