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diff --git a/runtime/CSharp3/Sources/Antlr3.Runtime.Debug/Misc/Stats.cs b/runtime/CSharp3/Sources/Antlr3.Runtime.Debug/Misc/Stats.cs
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+/*
+ * [The "BSD licence"]
+ * Copyright (c) 2005-2008 Terence Parr
+ * All rights reserved.
+ *
+ * Conversion to C#:
+ * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+namespace Antlr.Runtime.Misc
+{
+    using System.Collections.Generic;
+
+    using Directory = System.IO.Directory;
+    using Environment = System.Environment;
+    using File = System.IO.File;
+    using Math = System.Math;
+    using Path = System.IO.Path;
+
+    /** <summary>Stats routines needed by profiler etc...</summary>
+     *
+     *  <remarks>
+     *  note that these routines return 0.0 if no values exist in the X[]
+     *  which is not "correct", but it is useful so I don't generate NaN
+     *  in my output
+     *  </remarks>
+     */
+    public class Stats
+    {
+        public const string ANTLRWORKS_DIR = "antlrworks";
+
+        /** <summary>Compute the sample (unbiased estimator) standard deviation following:</summary>
+         *
+         *  <remarks>
+         *  Computing Deviations: Standard Accuracy
+         *  Tony F. Chan and John Gregg Lewis
+         *  Stanford University
+         *  Communications of ACM September 1979 of Volume 22 the ACM Number 9
+         *
+         *  The "two-pass" method from the paper; supposed to have better
+         *  numerical properties than the textbook summation/sqrt.  To me
+         *  this looks like the textbook method, but I ain't no numerical
+         *  methods guy.
+         *  </remarks>
+         */
+        public static double Stddev( int[] X )
+        {
+            int m = X.Length;
+            if ( m <= 1 )
+            {
+                return 0;
+            }
+            double xbar = Average(X);
+            double s2 = 0.0;
+            for ( int i = 0; i < m; i++ )
+            {
+                s2 += ( X[i] - xbar ) * ( X[i] - xbar );
+            }
+            s2 = s2 / ( m - 1 );
+            return Math.Sqrt( s2 );
+        }
+        public static double Stddev( List<int> X )
+        {
+            int m = X.Count;
+            if ( m <= 1 )
+            {
+                return 0;
+            }
+            double xbar = Average(X);
+            double s2 = 0.0;
+            for ( int i = 0; i < m; i++ )
+            {
+                s2 += ( X[i] - xbar ) * ( X[i] - xbar );
+            }
+            s2 = s2 / ( m - 1 );
+            return Math.Sqrt( s2 );
+        }
+
+        /** <summary>Compute the sample mean</summary> */
+        public static double Average(ICollection<int> X)
+        {
+            if (X.Count == 0)
+                return 0.0;
+
+            double sum = 0.0;
+            foreach (int i in X)
+                sum += i;
+
+            return sum / X.Count;
+        }
+
+        public static void WriteReport( string filename, string data )
+        {
+            string absoluteFilename = GetAbsoluteFileName( filename );
+
+            Directory.CreateDirectory( Path.GetDirectoryName( absoluteFilename ) );
+            File.AppendAllText( absoluteFilename, data );
+        }
+
+        public static string GetAbsoluteFileName( string filename )
+        {
+            string personalFolder = Environment.GetFolderPath( Environment.SpecialFolder.Personal );
+            return personalFolder + Path.DirectorySeparatorChar +
+                        ANTLRWORKS_DIR + Path.DirectorySeparatorChar +
+                        filename;
+        }
+    }
+}