svn commit: r674067 - /lucene/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/correlation/AbstractCorrelation.java

[srowen]

Author: srowen
Date: Fri Jul  4 07:25:17 2008
New Revision: 674067

URL: http://svn.apache.org/viewvc?rev=674067&view=rev
Log:
Math simplifications from turati -- thanks

Modified:
    
lucene/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/correlation/AbstractCorrelation.java

Modified: 
lucene/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/correlation/AbstractCorrelation.java
URL: 
http://svn.apache.org/viewvc/lucene/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/correlation/AbstractCorrelation.java?rev=674067&r1=674066&r2=674067&view=diff
==============================================================================
--- 
lucene/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/correlation/AbstractCorrelation.java
 (original)
+++ 
lucene/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/correlation/AbstractCorrelation.java
 Fri Jul  4 07:25:17 2008
@@ -218,9 +218,12 @@
     double n = (double) count;
     double meanX = sumX / n;
     double meanY = sumY / n;
-    double centeredSumXY = sumXY - meanY * sumX - meanX * sumY + n * meanX * 
meanY;
-    double centeredSumX2 = sumX2 - 2.0 * meanX * sumX + n * meanX * meanX;
-    double centeredSumY2 = sumY2 - 2.0 * meanY * sumY + n * meanY * meanY;
+    // double centeredSumXY = sumXY - meanY * sumX - meanX * sumY + n * meanX 
* meanY;
+    double centeredSumXY = sumXY - meanY * sumX;
+    // double centeredSumX2 = sumX2 - 2.0 * meanX * sumX + n * meanX * meanX;
+    double centeredSumX2 = sumX2 - meanX * sumX;
+    // double centeredSumY2 = sumY2 - 2.0 * meanY * sumY + n * meanY * meanY;
+    double centeredSumY2 = sumY2 - meanY * sumY;
 
     double result = computeResult(count, centeredSumXY, centeredSumX2, 
centeredSumY2, sumXYdiff2);
 
@@ -303,9 +306,12 @@
     double n = (double) count;
     double meanX = sumX / n;
     double meanY = sumY / n;
-    double centeredSumXY = sumXY - meanY * sumX - meanX * sumY + n * meanX * 
meanY;
-    double centeredSumX2 = sumX2 - 2.0 * meanX * sumX + n * meanX * meanX;
-    double centeredSumY2 = sumY2 - 2.0 * meanY * sumY + n * meanY * meanY;
+    // double centeredSumXY = sumXY - meanY * sumX - meanX * sumY + n * meanX 
* meanY;
+    double centeredSumXY = sumXY - meanY * sumX;
+    // double centeredSumX2 = sumX2 - 2.0 * meanX * sumX + n * meanX * meanX;
+    double centeredSumX2 = sumX2 - meanX * sumX;
+    // double centeredSumY2 = sumY2 - 2.0 * meanY * sumY + n * meanY * meanY;
+    double centeredSumY2 = sumY2 - meanY * sumY;
 
     double result = computeResult(count, centeredSumXY, centeredSumX2, 
centeredSumY2, sumXYdiff2);