/**
 * A tiny class to illustrate empirical timing in Java
 * 
 * @author gtowell Created: Feb 9, 2020
 */
public class Timer {
	private static final int REPS = 10; // number of trials
	private static final int NANOS_SEC = 1000000000; // nanosec per sec

	/**
	 * A function to really do nothing
	 * 
	 * @param data the size fo the data array affects the runtime of the method
	 * @return the sum of the square roots of the two index variables. Why? Why not!
	 */
	public double doSomething(int[] data) {
		double k = 0;
		for (long i = 0; i < data.length; i++) {
			for (long j = 0; j < data.length; j++) {
				k += Math.sqrt(i * j);
			}
		}
		return k;
	}

	/**
	 * Run an empirical study of the doSomething algorithm
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		Timer timer = new Timer();
		long data[] = new long[REPS];
		for (int j = 1000; j < 10001; j = j + 1000) {
			for (int i = 0; i < REPS; i++) {
				long start = System.nanoTime();
				timer.doSomething(new int[j]);
				long finish = System.nanoTime();
				data[i] = (finish - start);
				System.out.println(String.format("%d %.4f", j, (double) (finish - start) / NANOS_SEC));
			}
		}
	}
}