Index: src/Common/NetTopologySuite/Algorithm/SIRtreePointInRing.cs
===================================================================
diff -u -r8f6ae890fed8e8eae3a32f9c0498a10f82e0ddf9 -r5fc71a385897af92ccb092f2f969b5709afab85a
--- src/Common/NetTopologySuite/Algorithm/SIRtreePointInRing.cs	(.../SIRtreePointInRing.cs)	(revision 8f6ae890fed8e8eae3a32f9c0498a10f82e0ddf9)
+++ src/Common/NetTopologySuite/Algorithm/SIRtreePointInRing.cs	(.../SIRtreePointInRing.cs)	(revision 5fc71a385897af92ccb092f2f969b5709afab85a)
@@ -8,11 +8,11 @@
     /// <summary> 
     /// Implements <c>PointInRing</c> using a <c>SIRtree</c> index to increase performance.
     /// </summary>
-    public class SIRtreePointInRing : IPointInRing 
+    public class SIRtreePointInRing : IPointInRing
     {
-        private ILinearRing ring;
+        private readonly ILinearRing ring;
         private SIRtree sirTree;
-        private int crossings = 0;  // number of segment/ray crossings
+        private int crossings = 0; // number of segment/ray crossings
 
         /// <summary>
         /// 
@@ -27,32 +27,15 @@
         /// <summary>
         /// 
         /// </summary>
-        private void BuildIndex()
-        {
-            sirTree = new SIRtree();
-            ICoordinate[] pts = ring.Coordinates;
-            for (int i = 1; i < pts.Length; i++) 
-            {
-                if (pts[i - 1].Equals(pts[i])) 
-                    continue;
-
-                LineSegment seg = new LineSegment(pts[i - 1], pts[i]);
-                sirTree.Insert(seg.P0.Y, seg.P1.Y, seg);
-            }
-        }
-
-        /// <summary>
-        /// 
-        /// </summary>
         /// <param name="pt"></param>
         /// <returns></returns>
         public bool IsInside(ICoordinate pt)
         {
             crossings = 0;
 
             // test all segments intersected by vertical ray at pt
-            IList segs = sirTree.Query(pt.Y);        
-            for(IEnumerator i = segs.GetEnumerator(); i.MoveNext(); ) 
+            IList segs = sirTree.Query(pt.Y);
+            for (IEnumerator i = segs.GetEnumerator(); i.MoveNext();)
             {
                 LineSegment seg = (LineSegment) i.Current;
                 TestLineSegment(pt, seg);
@@ -61,20 +44,41 @@
             /*
             *  p is inside if number of crossings is odd.
             */
-            if ((crossings % 2) == 1) 
-                return true;            
+            if ((crossings%2) == 1)
+            {
+                return true;
+            }
             return false;
         }
 
         /// <summary>
         /// 
         /// </summary>
+        private void BuildIndex()
+        {
+            sirTree = new SIRtree();
+            ICoordinate[] pts = ring.Coordinates;
+            for (int i = 1; i < pts.Length; i++)
+            {
+                if (pts[i - 1].Equals(pts[i]))
+                {
+                    continue;
+                }
+
+                LineSegment seg = new LineSegment(pts[i - 1], pts[i]);
+                sirTree.Insert(seg.P0.Y, seg.P1.Y, seg);
+            }
+        }
+
+        /// <summary>
+        /// 
+        /// </summary>
         /// <param name="p"></param>
         /// <param name="seg"></param>
-        private void TestLineSegment(ICoordinate p, LineSegment seg) 
+        private void TestLineSegment(ICoordinate p, LineSegment seg)
         {
-            double xInt;  // x intersection of segment with ray
-            double x1;    // translated coordinates
+            double xInt; // x intersection of segment with ray
+            double x1; // translated coordinates
             double y1;
             double x2;
             double y2;
@@ -89,19 +93,21 @@
             x2 = p2.X - p.X;
             y2 = p2.Y - p.Y;
 
-            if (((y1 > 0) && (y2 <= 0)) || ((y2 > 0) && (y1 <= 0))) 
+            if (((y1 > 0) && (y2 <= 0)) || ((y2 > 0) && (y1 <= 0)))
             {
                 /*
                 *  segment straddles x axis, so compute intersection.
                 */
-                xInt = RobustDeterminant.SignOfDet2x2(x1, y1, x2, y2) / (y2 - y1);
-                
+                xInt = RobustDeterminant.SignOfDet2x2(x1, y1, x2, y2)/(y2 - y1);
+
                 /*
                 *  crosses ray if strictly positive intersection.
                 */
-                if (0.0 < xInt) 
-                    crossings++;            
+                if (0.0 < xInt)
+                {
+                    crossings++;
+                }
             }
         }
     }
-}
+}
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