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From Luc Maisonobe <Luc.Maison...@free.fr>
Subject Re: [math] sum of logs in summary statistics
Date Sat, 09 Feb 2008 18:14:52 GMT
Phil Steitz a écrit :
> On Feb 8, 2008 7:00 AM,  <luc.maisonobe@free.fr> wrote:
>> luc.maisonobe@free.fr wrote:
>>
>>> In addition to the statistics required by the StatisticalSummary interface it
>>> implements, the SummaryStatistics class computes the sum of squares and the
>>> sum
>>> of logs. It also has setters and getters for the underlying statistics
>>> implementations. However, it does not provide a getSumlg method.
>> The sum of logs is also not used in the equals, hash and toString methods.
>>
>> Luc
>>
>>
>>> Should the sum of logs computation be deprecated or a getSumlg method added ?
>>>
> 
> Interesting.  This is likely a result of refactoring several years
> back when the geometric mean computation used the sum of logs
> instance.  Now it does not, so it is either wasted computation or
> something of value not exposed to the user.  Makes sense to me to add
> getSumLog to SummaryStatistics.  It doesn't need to be included in
> equals or hashcode since geo mean + N equivalence implies log sum
> equivalence.
> 
> Looking again at the code, I now see it as stupid that geometricMean
> in SummaryStatistics does not use the sumOfLogs instance.  If
> geometricMean exposed a setter for its internally wrapped sumOfLogs
> instance, we could just set that in SummaryStatistics and only
> increment the sumOfLogs instance.  It would probably also be an
> improvment for geometricMean to expose a setter for this.
> 
> If there are no objections, I will go ahead and make these changes.
> Thanks for pointing this out, luc.

Go ahead with that.

If you could also have a glimpse at the multivariate summary statistics 
I added yesterday, I would be happy. During my paid work day (in the 
space industry), I am in the process of switching several projects from 
Mantissa to [math] and needed this feature.

I am aware this was really done in a hurry. I have tried to be as 
compliant with univariate statistics as possible, but may have 
completely missed something. I have reused the VectorialCovariance class 
I commited one year ago, but it does not follow the general architecture 
of other statistics. I would really like to have your thoughts about this.

Luc

> 
> Phil
> 
> Phil
> 
> 
>>> Luc
>>
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