> I really need a Standard Deviation aggregate function...
> 
> I know about the man pages for "create aggregate" and "create
> function".  Is there something else I should look at?
> 
> It seems kind of hard to do with only two state functions unless
> I "cheat".  I need to keep three values, Count, Sum, and Sum of
> Squares.
> 
> Any hints or advice??

I thought about this a long time ago and had an idea but never
got around to trying to implement it.  I was going to have some
functions that worked on a structure of two doubles to track
the sum and square instead of using only one simple type.

darrenk

In response to

• Standard Deviation function. at 1998-06-05 01:20:50 from Chris Albertson

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• Re: [HACKERS] Standard Deviation function. at 1998-06-05 01:55:07 from Bruce Momjian

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Next:	From: Bruce Momjian	Date: 1998-06-05 01:55:07
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