@Test
public void asDoubleMatrix() {

  double[] array1 = {0, 1, 2};
  double[] array2 = {0, 1, 2};
  DoubleColumn c1 = DoubleColumn.create("1", array1);
  DoubleColumn c2 = DoubleColumn.create("2", array2);
  Table table = Table.create("test", c1, c2);
  double[][] expected = {{0.0, 0.0}, {1.0, 1.0}, {2.0, 2.0}};
  double[][] results = table.as().doubleMatrix();
  assertTrue(Arrays.deepEquals(expected, results));
}