On Sat, 29 Jul 2006, Peter Eisentraut wrote:
Sergey E. Koposov wrote:
I think since we are supporting the numeric type as a special
high-precision type, Postgres must have the high-precision
versions of all computational functions. Just my opinion.
Another way to look at it is whether you want to have accurate
computations (numeric) or approximate computations (float). I'm not a
statistician, so I don't know what most of these functions are used
for. From a mathematician's point of view, however, some of these
functions normally produce irrational numbers anyway, so it seems
unlikely that numeric will be useful. But looking at the definition
of, say, regr_avgx(Y, X), if all the input values are integers, it
might be useful if I could get an exact integer or rational number as
output, instead of a float, that is.
Exactly from the statistical point of view, there is no need to have the
integer output of those 2-arg. aggregates. For example corr(), regr_*()
are by definition not integer (they just don't have any sense as
integers...)( -1<= corr(Y,X)<=1 ) (for example the stddev(int) do
not produce int also, because it does not have any sense)
So it's perfectly fine that they are producing only floating numbers...
Regards,
Sergey
*******************************************************************
Sergey E. Koposov
Max Planck Institute for Astronomy/Sternberg Astronomical Institute
Tel: +49-6221-528-349
Web: http://lnfm1.sai.msu.ru/~math
E-mail: [EMAIL PROTECTED]
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