@Test public void testSum() { double[] vals = {1, 2, 3, 4, 5, 6, 7, 8}; DoubleVector vec = new DenseDoubleVector(vals); double expected = 0; double res = vec.sum(); for (int i = 0; i < vals.length; ++i) { expected += vec.get(i); } assertEquals(expected, res, 0.000001); }