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Date: Fri, 9 Nov 2012 17:39:56 +0100
From: Gilles Sadowski <gilles@harfang.homelinux.org>
To: dev@commons.apache.org
Subject: Re: [math] Math-817 and .equals questions.    .
Message-ID: <20121109163956.GV20488@dusk.harfang.homelinux.org>
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Hi Jared.

> Any thoughts on the below email?  If not, I will submit one patch, probably today or tomorrow.
> 
> -------------------------------
> 
> Hello,
> 
> I am about to submit some code for issue Math-817 involving fitting multivariate normal mixture models using the EM algorithm.  In order to simplify the unit test, I added overrode equals and hashCode.  This in turn required me to make a few changes to code in the previously resolved issues Math-815 and Math-816.  Am I supposed to just send one patch to 817, or am I supposed to break the patches up according to issue number?
> 
> Also, I notice the equals method in org.apache.commons.math3.linear.AbstractRealMatrix directly compares the results of getEntry(), which are often doubles.  Is this OK?  I don't have a great deal of experience in overriding equals where doubles are involved.  I have read that it is a good idea to use Double.doubleToLongBits and the use "==" or "!=".
> 
> http://www.javapractices.com/topic/TopicAction.do?Id=17
> 

It will be better to have a discussion based on some actual code.
[If you need a feature for MATH-817, it's fine to add it in the same patch.]


Best regards,
Gilles

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