Changeset 17125 for trunk/HeuristicLab.Problems.DataAnalysis.Symbolic

Timestamp:

07/11/19 11:20:58 (5 years ago)

Author:

gkronber

Message:

#2948: added support for tanh in DerivativeCalculator and a unit test case

File:

• trunk/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Converters/DerivativeCalculator.cs (modified) (1 diff)

trunk/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Converters/DerivativeCalculator.cs

@@ -179 +179 @@
         var u = (ISymbolicExpressionTreeNode)branch.GetSubtree(0).Clone();
         return Div(fxp, Square(Cosine(u)));
+      }
+      if (branch.Symbol is HyperbolicTangent) {
+        // tanh(f(x))' = f(x)'sech²(f(x)) = f(x)'(1 - tanh²(f(x)))
+        var fxp = Derive(branch.GetSubtree(0), variableName);
+        var tanh = (ISymbolicExpressionTreeNode)branch.Clone();
+        return Product(fxp, Subtract(CreateConstant(1.0), Square(tanh)));
       }
       throw new NotSupportedException(string.Format("Symbol {0} is not supported.", branch.Symbol));