svn commit: r1222443 - /mahout/trunk/core/src/main/java/org/apache/mahout/clustering/dirichlet/models/GaussianCluster.java

[jeastman]

Author: jeastman
Date: Thu Dec 22 20:43:26 2011
New Revision: 1222443

URL: http://svn.apache.org/viewvc?rev=1222443&view=rev
Log:
MAHOUT-846: Minor refactoring to eliminate unnecessary vector.times(SQRT2PI)

Modified:
    
mahout/trunk/core/src/main/java/org/apache/mahout/clustering/dirichlet/models/GaussianCluster.java

Modified: 
mahout/trunk/core/src/main/java/org/apache/mahout/clustering/dirichlet/models/GaussianCluster.java
URL: 
http://svn.apache.org/viewvc/mahout/trunk/core/src/main/java/org/apache/mahout/clustering/dirichlet/models/GaussianCluster.java?rev=1222443&r1=1222442&r2=1222443&view=diff
==============================================================================
--- 
mahout/trunk/core/src/main/java/org/apache/mahout/clustering/dirichlet/models/GaussianCluster.java
 (original)
+++ 
mahout/trunk/core/src/main/java/org/apache/mahout/clustering/dirichlet/models/GaussianCluster.java
 Thu Dec 22 20:43:26 2011
@@ -52,16 +52,14 @@ public class GaussianCluster extends Abs
   public double pdf(VectorWritable vw) {
     Vector x = vw.get();
     Vector m = getCenter();
-    Vector s = getRadius().plus(0.0000001); // add a small prior to avoid 
divide
-                                            // by zero
-    return Math.exp(-(divideSquareAndSum(x.minus(m), s) / 2))
-        / zProd(s.times(UncommonDistributions.SQRT2PI));
+    Vector s = getRadius().plus(0.0000001); // add a small prior to avoid 
divide by zero
+    return Math.exp(-(divideSquareAndSum(x.minus(m), s) / 2)) / zProdSqt2Pi(s);
   }
   
-  private double zProd(Vector s) {
+  private double zProdSqt2Pi(Vector s) {
     double prod = 1;
     for (int i = 0; i < s.size(); i++) {
-      prod *= s.getQuick(i);
+      prod *= s.getQuick(i) * UncommonDistributions.SQRT2PI;
     }
     return prod;
   }