@Test
public void testGetValues() {

  DenseMatrix m = new DenseMatrix(10, 10);
  for (int i = 0; i < 10; i++) {
    for (int j = 0; j < 10; j++) {
      m.set(i, j, 10 * i + j);
    }
  }
  double[][] values = m.getBackingStructure();
  Assert.assertEquals(values.length, 10);
  Assert.assertEquals(values[0].length, 10);
  Assert.assertEquals(values[9][9], 99.0, 0.0);
}