public void testPlusEquals() {
    HashedSparseVector s = (HashedSparseVector) s1.cloneMatrix();
    s.plusEqualsSparse(s2, 2.0);
    checkAnswer(s, new double[] {3, 5, 7, 6, 7});

    HashedSparseVector s2p = new HashedSparseVector(new int[] {13}, new double[] {0.8});
    s.plusEqualsSparse(s2p, 1.0);
    checkAnswer(s, new double[] {3, 5, 7, 6.8, 7});

    HashedSparseVector s3p = new HashedSparseVector(new int[] {14}, new double[] {0.8});
    s.plusEqualsSparse(s3p, 1.0);
    checkAnswer(s, new double[] {3, 5, 7, 6.8, 7}); // verify s unchanged

    HashedSparseVector s4 =
        new HashedSparseVector(new int[] {7, 14, 15}, new double[] {0.2, 0.8, 1.2});
    s.plusEqualsSparse(s4, 1.0);
    checkAnswer(s, new double[] {3, 5, 7.2, 6.8, 8.2});

    HashedSparseVector s5 = new HashedSparseVector(new int[] {7}, new double[] {0.2});
    s5.plusEqualsSparse(s1);
    for (int i = 0; i < s5.numLocations(); i++) {
      assertEquals(7, s5.indexAtLocation(i));
      assertEquals(3.2, s5.valueAtLocation(i), 0.0);
    }

    HashedSparseVector s6 = new HashedSparseVector(new int[] {7}, new double[] {0.2});
    s6.plusEqualsSparse(s1, 3.5);
    for (int i = 0; i < s6.numLocations(); i++) {
      assertEquals(7, s6.indexAtLocation(i));
      assertEquals(10.7, s6.valueAtLocation(i), 0.0);
    }
  }
  public void testSetValue() {
    HashedSparseVector s = (HashedSparseVector) s1.cloneMatrix();
    s.setValue(5, 0.3);

    double[] ans = new double[] {1, 0.3, 3, 4, 5};
    for (int i = 0; i < s.numLocations(); i++) {
      assertTrue(s.valueAtLocation(i) == ans[i]);
    }
  }
  public void testBinaryVector() {
    HashedSparseVector binary1 =
        new HashedSparseVector(idxs, null, idxs.length, idxs.length, false, false, false);
    HashedSparseVector binary2 =
        new HashedSparseVector(idx2, null, idx2.length, idx2.length, false, false, false);

    assertEquals(3, binary1.dotProduct(binary2), 0.0001);
    assertEquals(3, binary2.dotProduct(binary1), 0.0001);

    assertEquals(15.0, binary1.dotProduct(s1), 0.0001);
    assertEquals(15.0, s1.dotProduct(binary1), 0.0001);

    assertEquals(9.0, binary2.dotProduct(s1), 0.0001);
    assertEquals(9.0, s1.dotProduct(binary2), 0.0001);

    HashedSparseVector dblVec = (HashedSparseVector) s1.cloneMatrix();
    dblVec.plusEqualsSparse(binary1);
    checkAnswer(dblVec, new double[] {2, 3, 4, 5, 6});

    HashedSparseVector dblVec2 = (HashedSparseVector) s1.cloneMatrix();
    dblVec2.plusEqualsSparse(binary2);
    checkAnswer(dblVec2, new double[] {2, 2, 4, 4, 6});
  }