Hey Thomas,

Did you actually mean to delete this?

Phil


-------- Forwarded Message --------
Subject:        [jira] [Deleted] (MATH-1164) Rare case for
updateMembershipMatrix() in FuzzyKMeansClusterer
Date:   Thu, 6 Nov 2014 20:19:34 +0000 (UTC)
From:   Thomas Neidhart (JIRA) <j...@apache.org>
Reply-To:       iss...@commons.apache.org
To:     iss...@commons.apache.org



     [ 
https://issues.apache.org/jira/browse/MATH-1164?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Thomas Neidhart deleted MATH-1164:
----------------------------------


> Rare case for updateMembershipMatrix() in FuzzyKMeansClusterer
> --------------------------------------------------------------
>
>                 Key: MATH-1164
>                 URL: https://issues.apache.org/jira/browse/MATH-1164
>             Project: Commons Math
>          Issue Type: Bug
>            Reporter: Pashutan Modaresi
>            Priority: Minor
>   Original Estimate: 1h
>  Remaining Estimate: 1h
>
> The function updateMembershipMatrix() in FuzzyKMeansClusterer assigns the 
> points to the cluster with the highest membership. Consider the following 
> case:
> If the distance between a point and the cluster center is zero, then we will 
> have a cluster membership of one, and all other membership values will be 
> zero.
> So the if condition:
> if (membershipMatrix[i][j] > maxMembership) {
>                     maxMembership = membershipMatrix[i][j];
>                     newCluster = j;
> }
> will never be true during the for loop and newCluster will remain -1. This 
> will throw an exception because of the line:
> clusters.get(newCluster)
>                     .addPoint(point);
> Adding the following condition can solve the problem:
> double d;
> if (sum == 0)
> d = 1;
> else
> d = 1.0/sum;



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