Re: Odd statistics behaviour in 7.2

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От Bruno Wolff III
Тема Re: Odd statistics behaviour in 7.2
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Msg-id 20020216202028.GA7882@wolff.to
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Ответ на Re: Odd statistics behaviour in 7.2  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Odd statistics behaviour in 7.2  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Fri, Feb 15, 2002 at 07:09:42PM -0500, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> 
> 3. The equation is numerically stable even when n is much smaller than
> N, because the only cancellation is in the term (n - f1) which we can
> compute exactly.  A lot of the other equations I looked at depend on
> series like (1 - n/N)**i which are going to be really nasty when n/N
> is tiny.

You can work with the above for n << N by using power series. For n << N,
(1 - n/N)**i ~= 1 - in/N.


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