Bugfix

- fixed negative sample from distribution for time

src/main/java/net/berack/upo/valpre/Main.java

@@ -6,7 +6,7 @@ public class Main {
     public static void main(String[] args) {
         // Parameters for the simulation
         var seed = System.nanoTime();
-        var total = 1000;
+        var total = 100000;
         var lambda = 1.0 / 4.5;
         var mu = 3.2;
         var sigma = 0.6;
@@ -22,8 +22,8 @@ public class Main {
         sim.addNode(node2);
 
         var maxDepartures = new EndSimulationCriteria.MaxDepartures("Queue", total);
-        var maxTime = new EndSimulationCriteria.MaxTime(1000.0);
-        var results = sim.run(maxDepartures, maxTime);
+        //var maxTime = new EndSimulationCriteria.MaxTime(1000.0);
+        var results = sim.run(maxDepartures);
 
         // Display the results
         for (var entry : results.entrySet()) {

src/main/java/net/berack/upo/valpre/NetSimulation.java

@@ -133,7 +133,7 @@ public class NetSimulation {
 
             if (event.node.maxServers > this.numServerBusy) {
                 this.numServerBusy++;
-                var time = event.node.distribution.sample(this.rng);
+                var time = event.node.getPositiveSample(this.rng);
                 var departure = Event.newDeparture(event.node, timeNow + time);
                 fel.add(departure);
             } else {
@@ -163,7 +163,7 @@ public class NetSimulation {
             if (this.queue.size() < this.numServerBusy) {
                 this.numServerBusy--;
             } else {
-                var time = event.node.distribution.sample(this.rng);
+                var time = event.node.getPositiveSample(this.rng);
                 var departure = Event.newDeparture(event.node, timeNow + time);
                 fel.add(departure);
             }
@@ -188,7 +188,7 @@ public class NetSimulation {
          */
         private void addArrivalIf(boolean condition, ServerNode node, double timeNow, PriorityQueue<Event> fel) {
             if (condition && node != null) {
-                var delay = node.distribution.sample(this.rng);
+                var delay = node.getPositiveSample(this.rng);
                 fel.add(Event.newArrival(node, timeNow + delay));
             }
         }

src/main/java/net/berack/upo/valpre/ServerNode.java

@@ -102,6 +102,22 @@ public class ServerNode {
         return null;
     }
 
+    /**
+     * Gets a positive sample from the distribution.
+     * This is useful if you need to generate a positive value from a distribution
+     * that can generate negative values. For example, the normal distribution.
+     * 
+     * @param rng The random number generator to use.
+     * @return A positive sample from the distribution.
+     */
+    public double getPositiveSample(Rng rng) {
+        double sample;
+        do {
+            sample = this.distribution.sample(rng);
+        } while (sample < 0);
+        return sample;
+    }
+
     /**
      * Determines if the node should spawn an arrival based on the number of
      * arrivals.