Re: [Boost-bugs] [Boost C++ Libraries] #6057: Lazy variance in accumulator gives wrong result when too high statistics

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6057: Lazy variance in accumulator gives wrong result when too high statistics
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-11-16 08:06:44

#6057: Lazy variance in accumulator gives wrong result when too high statistics
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  Reporter:  Johan <johan.luisier@…>          |       Owner:  troyer                   
      Type:  Bugs                             |      Status:  reopened                 
 Milestone:  To Be Determined                 |   Component:  accumulator              
   Version:  Boost 1.44.0                     |    Severity:  Problem                  
Resolution:                                   |    Keywords:  accumulator lazy_variance
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Changes (by troyer):

  * status:  closed => reopened
  * resolution:  worksforme =>

Comment:

 Thank you for the updated example which now indeed shows what you report.
 The reason is simply an overflow in the sum of squares. To avoid it just
 use double instead of signed int as sample type - just as you do in your
 own reference class where you store MeanSq also as double.

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/6057#comment:4>
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