Index: trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/HeuristicLab.Problems.DataAnalysis-3.3.csproj
===================================================================
--- trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/HeuristicLab.Problems.DataAnalysis-3.3.csproj	(revision 5383)
+++ trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/HeuristicLab.Problems.DataAnalysis-3.3.csproj	(revision 5384)
@@ -108,4 +108,5 @@
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Symbolic\Symbols\Root.cs" />
     <Compile Include="Symbolic\Symbols\Derivative.cs" />
     <Compile Include="Symbolic\Symbols\Integral.cs" />
Index: trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/FullFunctionalExpressionGrammar.cs
===================================================================
--- trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/FullFunctionalExpressionGrammar.cs	(revision 5383)
+++ trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/FullFunctionalExpressionGrammar.cs	(revision 5384)
@@ -54,4 +54,7 @@
       var log = new Logarithm();
       var pow = new Power();
+      pow.InitialFrequency = 0.0;
+      var root = new Root();
+      root.InitialFrequency = 0.0;
       var exp = new Exponential();
       var @if = new IfThenElse();
@@ -76,8 +79,8 @@
       laggedVariable.InitialFrequency = 0.0;
 
-      var allSymbols = new List<Symbol>() { add, sub, mul, div, mean, sin, cos, tan, log, pow, exp, @if, gt, lt, and, or, not, timeLag, integral, derivative, constant, variableSymbol, laggedVariable };
+      var allSymbols = new List<Symbol>() { add, sub, mul, div, mean, sin, cos, tan, log, pow, root, exp, @if, gt, lt, and, or, not, timeLag, integral, derivative, constant, variableSymbol, laggedVariable };
       var unaryFunctionSymbols = new List<Symbol>() { sin, cos, tan, log, exp, not, timeLag, integral, derivative };
 
-      var binaryFunctionSymbols = new List<Symbol>() { pow, gt, lt };
+      var binaryFunctionSymbols = new List<Symbol>() { pow, root, gt, lt };
       var functionSymbols = new List<Symbol>() { add, sub, mul, div, mean, and, or };
       var terminalSymbols = new List<Symbol>() { variableSymbol, constant, laggedVariable };
Index: trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SimpleArithmeticExpressionInterpreter.cs
===================================================================
--- trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SimpleArithmeticExpressionInterpreter.cs	(revision 5383)
+++ trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/SimpleArithmeticExpressionInterpreter.cs	(revision 5384)
@@ -67,7 +67,8 @@
 
       public const byte Power = 22;
-      public const byte TimeLag = 23;
-      public const byte Integral = 24;
-      public const byte Derivative = 25;
+      public const byte Root = 23;
+      public const byte TimeLag = 24;
+      public const byte Integral = 25;
+      public const byte Derivative = 26;
     }
 
@@ -95,7 +96,8 @@
       { typeof(Argument), OpCodes.Arg },
       { typeof(Power),OpCodes.Power},
+      { typeof(Root),OpCodes.Root},
       { typeof(TimeLag), OpCodes.TimeLag}, 
       { typeof(Integral), OpCodes.Integral},
-      {typeof(Derivative), OpCodes.Derivative},
+      { typeof(Derivative), OpCodes.Derivative},
     };
     private const int ARGUMENT_STACK_SIZE = 1024;
@@ -196,6 +198,11 @@
         case OpCodes.Power: {
             double x = Evaluate(dataset, ref row, code, ref pc, argumentStack, ref argStackPointer);
-            double y = Evaluate(dataset, ref row, code, ref pc, argumentStack, ref argStackPointer);
+            double y = Math.Round(Evaluate(dataset, ref row, code, ref pc, argumentStack, ref argStackPointer));
             return Math.Pow(x, y);
+          }
+        case OpCodes.Root: {
+            double x = Evaluate(dataset, ref row, code, ref pc, argumentStack, ref argStackPointer);
+            double y = Math.Round(Evaluate(dataset, ref row, code, ref pc, argumentStack, ref argStackPointer));
+            return Math.Pow(x, 1 / y);
           }
         case OpCodes.Exp: {
Index: trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/Symbols/Root.cs
===================================================================
--- trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/Symbols/Root.cs	(revision 5384)
+++ trunk/sources/HeuristicLab.Problems.DataAnalysis/3.3/Symbolic/Symbols/Root.cs	(revision 5384)
@@ -0,0 +1,38 @@
+#region License Information
+/* HeuristicLab
+ * Copyright (C) 2002-2010 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
+ *
+ * This file is part of HeuristicLab.
+ *
+ * HeuristicLab is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * HeuristicLab is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
+ */
+#endregion
+
+using HeuristicLab.Common;
+using HeuristicLab.Core;
+using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.Symbols;
+using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
+namespace HeuristicLab.Problems.DataAnalysis.Symbolic.Symbols {
+  [StorableClass]
+  [Item("Root", "Symbol that represents the n-th root function.")]
+  public sealed class Root : Symbol {
+    [StorableConstructor]
+    private Root(bool deserializing) : base(deserializing) { }
+    private Root(Root original, Cloner cloner) : base(original, cloner) { }
+    public override IDeepCloneable Clone(Cloner cloner) {
+      return new Root(this, cloner);
+    }
+    public Root() : base("Root", "Symbol that represents the n-th root function.") { }
+  }
+}
