class SparseVector extends Vector {

	@Override
	public double normL2Square() {
		double d = 0;
		for (double t : values) {
			d += t * t;
		}
		return d;
	}

	public  SparseVector();
	public  SparseVector(int n);
	public  SparseVector(int n, int[] indices, double[] values);
	public  SparseVector(int n, Map<Integer, Double> kv);

}