@Test
public void testMinus() throws Exception {

    Vector d = v2.minus(v1);
    Assert.assertEquals(d.get(0), 0.0, TOL);
    Assert.assertEquals(d.get(1), -2.0, TOL);
    Assert.assertEquals(d.get(2), 0.0, TOL);
    Assert.assertEquals(d.get(3), -1.0, TOL);
    Assert.assertEquals(d.get(4), 1.0, TOL);
}