SparseVector extends Vector { @Override public Vector plus(Vector vec) { if (this.size() != vec.size()) { throw new IllegalArgumentException("The size of the two vectors are different."); } if (vec instanceof DenseVector) { DenseVector r = ((DenseVector) vec).clone(); for (int i = 0; i < this.indices.length; i++) { r.add(this.indices[i], this.values[i]); } return r; } else { return MatVecOp.apply(this, (SparseVector) vec, ((a, b) -> a + b)); } } SparseVector();  SparseVector(int n);  SparseVector(int n, int[] indices, double[] values);  SparseVector(int n, Map<Integer, Double> kv); @Override SparseVector clone(); @Override SparseVector prefix(double d); @Override SparseVector append(double d); int[] getIndices(); double[] getValues(); @Override int size(); @Override double get(int i); void setSize(int n); int numberOfValues(); @Override void set(int i, double val); @Override void add(int i, double val); @Override String toString(); @Override double normL2(); @Override double normL1(); @Override double normInf(); @Override double normL2Square(); @Override SparseVector slice(int[] indices); @Override Vector plus(Vector vec); @Override Vector minus(Vector vec); @Override SparseVector scale(double d); @Override void scaleEqual(double d); void removeZeroValues(); @Override double dot(Vector other); @Override DenseMatrix outer(); DenseMatrix outer(SparseVector other); DenseVector toDenseVector(); @Override void standardizeEqual(double mean, double stdvar); @Override void normalizeEqual(double p); @Override boolean equals(Object o); @Override int hashCode(); void forEach(BiConsumer<Integer, Double> action); @Override VectorIterator iterator();  }
@Test public void testPlus() throws Exception { Vector d = v1.plus(v2); 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), 3.0, TOL); DenseVector dv = DenseVector.ones(8); dv = dv.plus(v2); Assert.assertArrayEquals(dv.getData(), new double[]{1, 1, 1, 2, 2, 2, 1, 1}, TOL); }