Thanks, 2008/10/26 Luc Maisonobe <[EMAIL PROTECTED]>
> nicolas de loof a écrit : > > Hello > > For the monitoring component I've got a set of values. I'd like to > compute > > the std. deviation, but as I don't store the full values but only > aggregates > > (sum, sum of squares) I can't use commons-math StandardDeviation. > > > > Is there anything in commons-math for such use case ? I've found at > > http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance some > > algorithm to compute "an > > unbiased<http://en.wikipedia.org/wiki/Estimator_bias> estimate", > > but if something stable and tested is available in math I'd prefer not to > > reinvent the wheel ! > > > > Nicolas > > > > The various classes dealing with such features are designed to be built > empty and to be updated at each sample element. For example the > SummaryStatistics and DescriptiveStatistics classes provide an addValue > method whereas all implementations of StorelessUnivariateStatistics > provide an increment method. > > These methods take care of computing the sum and sum of squares for you. > The SummaryStatistics class maintains many values in addition to these > ones (min, max ...). Could you use these classes instead of storing the > data by yourself and later computing the results ? > > Luc > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > >
