@Test
public void testUOrthogonal() {

  checkOrthogonal(new SingularValueDecomposition(new DenseMatrix(testSquare)).getU());
  checkOrthogonal(new SingularValueDecomposition(new DenseMatrix(testNonSquare)).getU());
  checkOrthogonal(new SingularValueDecomposition(new DenseMatrix(testNonSquare).transpose()).getU());
}