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From tomm...@apache.org
Subject svn commit: r1408773 - /hama/trunk/ml/src/main/java/org/apache/hama/ml/regression/LogisticRegressionModel.java
Date Tue, 13 Nov 2012 15:09:48 GMT
Author: tommaso
Date: Tue Nov 13 15:09:47 2012
New Revision: 1408773

URL: http://svn.apache.org/viewvc?rev=1408773&view=rev
Log:
[HAMA-668] - added an assertion to check h to be within 0 and 1

Modified:
    hama/trunk/ml/src/main/java/org/apache/hama/ml/regression/LogisticRegressionModel.java

Modified: hama/trunk/ml/src/main/java/org/apache/hama/ml/regression/LogisticRegressionModel.java
URL: http://svn.apache.org/viewvc/hama/trunk/ml/src/main/java/org/apache/hama/ml/regression/LogisticRegressionModel.java?rev=1408773&r1=1408772&r2=1408773&view=diff
==============================================================================
--- hama/trunk/ml/src/main/java/org/apache/hama/ml/regression/LogisticRegressionModel.java
(original)
+++ hama/trunk/ml/src/main/java/org/apache/hama/ml/regression/LogisticRegressionModel.java
Tue Nov 13 15:09:47 2012
@@ -30,7 +30,10 @@ public class LogisticRegressionModel imp
     costFunction = new CostFunction() {
       @Override
       public double calculateCostForItem(DoubleVector x, double y, int m, DoubleVector theta,
HypothesisFunction hypothesis) {
-        return (-1 * y * Math.log(applyHypothesis(theta, x)) + (1 - y) * Math.log(1 - applyHypothesis(theta,
x))) / m;
+          double h = applyHypothesis(theta, x);
+          assert h > 0 && h < 1 : new StringBuilder("cannot calculate the log
of a number equal to / less than zero [h:").
+                  append(h).append(" in log(h) and log(1-h)]").toString();
+          return (-1 * y * Math.log(h) + (1 - y) * Math.log(1 - h)) / m;
       }
     };
   }



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