Winfried Donkers W.Donkers at dci-electronics.nl
Thu Sep 14 07:18:23 UTC 2017

Hi Eike,

As we now have changed GEOMEAN, I think it would be wise to try to improve ODFF1.2 as well for GEOMEAN.


Van: LibreOffice [mailto:libreoffice-bounces at lists.freedesktop.org] Namens Winfried Donkers
Verzonden: woensdag 26 juli 2017 12:06
Aan: libreoffice at lists.freedesktop.org; Eike Rathke (erack at redhat.com)
Onderwerp: ODFF1.2 GEOMEAN

Hi Eike,

I'm looking at bug 109096.
The problem here is that ODFF1.2 does not have constraints for the number values and neither specifies a complete result description.
See http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part2.html#__RefHeading__1018690_715980110

Geometric mean is defined as n-root( a1 * a2 * ... * an). This applies for n positive values a#.
This is awkward to compute as overflow is lurking in case of large values a and a large number n.
An alternative computation is given in ODFF, but the case of any value a# being 0 is not mentioned (result is then 0).
Any a# with value is a geometrically valid situation, unlike negative values which do not have any geometric meaning AFAIK.

I would propose an amendment of ODFF1.2 for GEOMEAN:
Constraints: numbers >= 0
Semantics: addition of Returns zero when one or more numbers have value 0.

What's your opinion?


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