Changeset 6774

Timestamp:

09/15/11 16:56:16 (13 years ago)

Author:

gkronber

Message:

#1645: fixed bug related to simplification of logarithmic expressions

Location:

trunk/sources/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4

Files:

• SymbolicDataAnalysisExpressionTreeSimplifier.cs (modified) (1 diff)
• Tests/SymbolicDataAnalysisExpressionTreeSimplifierTest.cs (modified) (1 diff)

trunk/sources/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisExpressionTreeSimplifier.cs

@@ -538 +538 @@
       } else if (IsExp(node)) {
         return node.GetSubtree(0);
-      } else if (IsMultiplication(node)) {
-        return node.Subtrees.Select(s => MakeLog(s)).Aggregate((x, y) => MakeSum(x, y));
-      } else if (IsDivision(node)) {
-        var subtractionNode = subSymbol.CreateTreeNode();
-        foreach (var subtree in node.Subtrees) {
-          subtractionNode.AddSubtree(MakeLog(subtree));
-        }
-        return subtractionNode;
       } else {
         var logNode = logSymbol.CreateTreeNode();

trunk/sources/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Tests/SymbolicDataAnalysisExpressionTreeSimplifierTest.cs

@@ -131 +131 @@
       }
       {
-        // log transformation
-        var actualTree = simplifier.Simplify(importer.Import("(log (* (variable 2.0 a) (variable 3.0 b)))"));
-        var expectedTree = importer.Import("(+ (log (variable 1.0 a)) (log (variable 1.0 b)) 1.7918)");
-        Assert.AreEqual(formatter.Format(expectedTree), formatter.Format(actualTree));
-      }
-      {
-        // log transformation
-        var actualTree = simplifier.Simplify(importer.Import("(log (/ (variable 2.0 a) (variable 3.0 b)))"));
-        var expectedTree = importer.Import("(- (log (variable 2.0 a)) (log (variable 3.0 b)))");
+        // must not transform logs in this way as we do not know wether both variables are positive
+        var actualTree = simplifier.Simplify(importer.Import("(log (* (variable 1.0 a) (variable 1.0 b)))"));
+        var expectedTree = importer.Import("(log (* (variable 1.0 a) (variable 1.0 b)))");
+        Assert.AreEqual(formatter.Format(expectedTree), formatter.Format(actualTree));
+      }
+      {
+        // must not transform logs in this way as we do not know wether both variables are positive
+        var actualTree = simplifier.Simplify(importer.Import("(log (/ (variable 1.0 a) (variable 1.0 b)))"));
+        var expectedTree = importer.Import("(log (/ (variable 1.0 a) (variable 1.0 b)))");
         Assert.AreEqual(formatter.Format(expectedTree), formatter.Format(actualTree));
       }