> 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
> 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.
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