--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/backend/src/main/java/org/dive4elements/river/backend/utils/EpsilonComparator.java	Thu Sep 04 15:03:25 2014 +0200
@@ -0,0 +1,36 @@
+/* Copyright (C) 2011, 2012, 2013 by Bundesanstalt für Gewässerkunde
+ * Software engineering by Intevation GmbH
+ *
+ * This file is Free Software under the GNU AGPL (>=v3)
+ * and comes with ABSOLUTELY NO WARRANTY! Check out the
+ * documentation coming with Dive4Elements River for details.
+ */
+
+package org.dive4elements.river.backend.utils;
+
+import java.util.Comparator;
+import java.io.Serializable;
+
+/** Comparator with some tolerance (epsilon). */
+public class EpsilonComparator implements Comparator<Double>, Serializable
+{
+    public static final double EPSILON = 1e-4;
+
+    /** Ready-made comparator with 1e-4 tolerance. */
+    public static final EpsilonComparator CMP = new EpsilonComparator(EPSILON);
+
+    private double epsilon;
+
+    public EpsilonComparator(double epsilon) {
+        this.epsilon = epsilon;
+    }
+
+    @Override
+    public int compare(Double a, Double b) {
+        double diff = a - b;
+        if (diff < -epsilon) return -1;
+        if (diff >  epsilon) return +1;
+        return 0;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :