Changeset 14856

Timestamp:

04/13/17 11:15:47 (8 years ago)

Author:

gkronber

Message:

#2700: fixed bug in approximate gradient calculation

File:

• branches/TSNE/HeuristicLab.Algorithms.DataAnalysis/3.4/TSNE/TSNEStatic.cs (modified) (2 diffs)

branches/TSNE/HeuristicLab.Algorithms.DataAnalysis/3.4/TSNE/TSNEStatic.cs

@@ -437 +437 @@
       }
 
-      // TODO: there seems to be a bug in the error approximation.
       // The mapping of the approximate tSNE looks good but the error curve never changes.
       private static double EvaluateErrorApproximate(IReadOnlyList<int> rowP, IReadOnlyList<int> colP, IReadOnlyList<double> valP, double[,] y, double theta) {
@@ -627 +626 @@
       var row = new double[d];
       for(var n1 = 0; n1 < n; n1++) {
-        Buffer.BlockCopy(negF, (sizeof(double) * n1 * d), row, 0, d);
         tree.ComputeNonEdgeForces(n1, theta, row, ref sumQ);
+        Buffer.BlockCopy(row, 0, negF, (sizeof(double) * n1 * d), d*sizeof(double));
       }
 
       // Compute final t-SNE gradient
-      for(var i = 0; i < n; i++)
+      for (var i = 0; i < n; i++)
         for(var j = 0; j < d; j++) {
           dC[i, j] = posF[i, j] - negF[i, j] / sumQ;