Comparison.java

public static void main(String[] args) {
		fast();
		slow();
	}

	static void fast() {
		int hiddenDim = 200;
		int numChar = 100;
		int length = 500;
		int batchSize = 50;

		INDArray c2v = Nd4j.zeros(numChar, hiddenDim);

		INDArray h0 = Nd4j.zeros(batchSize, hiddenDim);
		INDArray c0 = Nd4j.zeros(batchSize, hiddenDim);

		INDArray fwdmap = Nd4j.zeros(batchSize, numChar);

		INDArray embed = fwdmap.mmul(c2v);

		List<INDArray> embeds = new ArrayList<>();
		List<INDArray> h0s = new ArrayList<>();
		for (int x = 0; x < 1000; x++) {
			embeds.add(Nd4j.createUninitialized(embed.shape()));
			h0s.add(Nd4j.createUninitialized(h0.shape()));
		}

		long sum = 0;

		for (int x = 0; x < embeds.size(); x++) {
			long time1 = System.nanoTime();
			INDArray concat = Nd4j.concat(1, embeds.get(x), h0s.get(x));
			long time2 = System.nanoTime();

			sum += time2 - time1;
		}
		System.out.println(sum / embeds.size());
	}

	static void slow() {
		int hiddenDim = 200;
		int numChar = 100;
		int length = 500;
		int batchSize = 50;

		INDArray c2v = Nd4j.zeros(numChar, hiddenDim);

		INDArray h0 = Nd4j.zeros(batchSize, hiddenDim);
		INDArray c0 = Nd4j.zeros(batchSize, hiddenDim);

		INDArray fwdmap = Nd4j.zeros(batchSize, numChar);

		INDArray embed = fwdmap.mmul(c2v);

		List<INDArray> embeds = new ArrayList<>();
		List<INDArray> h0s = new ArrayList<>();
		for (int x = 0; x < 1000; x++) {
			embeds.add(Nd4j.createUninitialized(embed.shape()));
			h0s.add(Nd4j.createUninitialized(h0.shape()));
		}

		long sum = 0;

		for (int x = 0; x < embeds.size(); x++) {
			embed = fwdmap.mmul(c2v);
			long time1 = System.nanoTime();
			INDArray concat = Nd4j.concat(1, embeds.get(x), h0s.get(x));
			long time2 = System.nanoTime();

			sum += time2 - time1;
		}
		System.out.println(sum / embeds.size());
	}

	static INDArray xavier(int[] shape) {
		int n = 1;
		for (int i = 0; i < shape.length - 1; i++)
			n *= shape[i];
		double sd = Math.sqrt(3d / n);
		return new UniformDistribution(-sd, sd).sample(shape);
	}