Leonardo Fernandez Sanchez created MAHOUT-1602:
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Summary: Euclidean Distance Similarity Math
Key: MAHOUT-1602
URL: https://issues.apache.org/jira/browse/MAHOUT-1602
Project: Mahout
Issue Type: Bug
Components: Collaborative Filtering, Math
Reporter: Leonardo Fernandez Sanchez
Within the file:
/mrlegacy/src/main/java/org/apache/mahout/cf/taste/impl/similarity/EuclideanDistanceSimilarity.java
Mentions that the implementation should be sqrt(n) / (1 + distance).
Once the equation is simplified, should be:
1 / ((1 + distance) / sqrt(n))
Coded:
return 1.0 / ((1.0 + Math.sqrt(sumXYdiff2)) / Math.sqrt(n));
But instead is (missing grouping brackets):
1 / (1 + distance / sqrt (n))
Coded:
return 1.0 / (1.0 + Math.sqrt(sumXYdiff2) / Math.sqrt(n));
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