QueueLindley.java

package tutorial;
 
import umontreal.ssj.stat.*;
import umontreal.ssj.rng.*;
import umontreal.ssj.probdist.ExponentialDist;
 
public class QueueLindley {
 
   RandomStream streamArr = new MRG32k3a();
   RandomStream streamServ = new MRG32k3a();
   Tally averageWaits = new Tally("Average waits");
 
   public double simulate(int numCust, double lambda, double mu) {
      double Wi = 0.0;
      double sumWi = 0.0;
      for (int i = 2; i <= numCust; i++) {
         Wi += ExponentialDist.inverseF(mu, streamServ.nextDouble())
               - ExponentialDist.inverseF(lambda, streamArr.nextDouble());
         if (Wi < 0.0)
            Wi = 0.0;
         sumWi += Wi;
      }
      return sumWi / numCust;
   }
 
   public void simulateRuns(int n, int numCust, double lambda, double mu) {
      averageWaits.init();
      for (int i = 0; i < n; i++)
         averageWaits.add(simulate(numCust, lambda, mu));
   }
 
   public static void main(String[] args) {
      QueueLindley queue = new QueueLindley();
      queue.simulateRuns(100, 10000, 1.0, 2.0);
      System.out.println(queue.averageWaits.report());
   }
}