public void periodicityReport (String outputName) throws IOException {
		if (!fileExists(outputName)) {
			FileWriter output = new FileWriter (outputName);
			output.write("#This is the periodicity report\n\n");
			putMetaData(output);
			for (Node n: graph.getNodes()) {
				for (Edge e: n.getAdj()) {
					output.write("Edge " + n.getName() + " " + e.getV().getName() + "\n");
					ArrayList<Integer> seq = e.buildSequence();
					int p = 0, seconds = 0;
					for (int i = 0; i < seq.size()/2; i++) {
						if (i > 0)
							seconds += seq.get(2*i - 1) + seq.get(2*i - 2);
						p = e.periodLength(i, seq);
						if (p > 0) {
							output.write("Periodic after " + seconds + " seconds, every " + p + " seconds.\n");
							break;
						}
					}
					if (p == 0)
						output.write("Non periodic.\n");
				}
			}
			output.close();
		}
	}