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From Dimitri Pourbaix <>
Subject Re: [math] speeding up percentile based statistics
Date Sat, 18 Sep 2010 18:01:08 GMT

If I understand correctly, the argument against the present implementation
is that if several percentiles are requested, they all require the sorting
of the array.  On the other hand, the speed-up version would no longer
be mathematically correct, as a rough approximate of the pivot would be
adopted.  There is a compromise which would satisfy both sides, is not
there?  What about sorting and storing the sorted version of the array,
once for all at the constructor level?  That is what one would do anyway
if speed was an issue (in one application, I need 5, 50, and 95-percentile
of the same aray and sort it only once!).

Dimitri Pourbaix                         *
Institut d'Astronomie et d'Astrophysique *      Don't worry, be happy
CP 226, office 2.N4.211, building NO     *         and CARPE DIEM.
Universite Libre de Bruxelles            *
Boulevard du Triomphe                    *      Tel : +32-2-650.35.71
  B-1050 Bruxelles                        *      Fax : +32-2-650.42.26     *

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