Changeset 14883 for branches/RBFRegression/HeuristicLab.Algorithms.DataAnalysis/3.4/RadialBasisFunctions/KernelFunctions/ThinPlatePolysplineKernel.cs

Timestamp:

04/24/17 13:17:43 (7 years ago)

Author:

bwerth

Message:

#2699 checked and reformulated gradient functions for kernels

File:

• branches/RBFRegression/HeuristicLab.Algorithms.DataAnalysis/3.4/RadialBasisFunctions/KernelFunctions/ThinPlatePolysplineKernel.cs (modified) (1 diff)

branches/RBFRegression/HeuristicLab.Algorithms.DataAnalysis/3.4/RadialBasisFunctions/KernelFunctions/ThinPlatePolysplineKernel.cs

@@ -46 +46 @@
 
     protected override double Get(double norm) {
-      if (Math.Pow(norm, Beta) <= 0) return 0;
-      return Math.Pow(norm, Beta * 2) * Math.Log(1 + Math.Pow(norm, Beta));
+      if (Math.Pow(norm, Beta) <= 0) return double.NaN;
+      return Math.Pow(norm, 2 * Beta) * Math.Log(1 + Math.Pow(norm, Beta));
     }
 
     protected override double GetGradient(double norm) {
       if (Math.Pow(norm, Beta) <= 0) return double.NaN;
-      var ax = Math.Pow(norm, Beta);
-      var a2x = ax * ax;
-      var a3x = a2x * ax;
-      var loga = Math.Log(norm);
-      return 2 * a2x * loga * Math.Log(ax + 1) + a3x * loga / (ax + 1);
+      return 2 * Math.Log(norm) * Math.Pow(norm, 2 * Beta) * Math.Log(1 + Math.Pow(norm, Beta)) + Math.Pow(norm, 3 * Beta) * Math.Log(norm) / (Math.Pow(norm, Beta) + 1);
     }
   }