Re: [h5md-user] units module

[Konrad Hinsen]

Pierre de Buyl writes:

 > I just toyed a bit with udunits2 and it seems very nice. The fact that we can
 > rely on this software if need is good.

Indeed. On the other hand, if we allow units to be as general as
allowed by udunits, this means that every program wanting to read H5MD
must either use udunits or re-implement a large subset of it.

 > In Mosaic [1], the restriction is, if I understand well:
 > 1. whitespace separation only (so no "." that is allowed with udunits).
 > 2. Not all units are allowed.
 > 3. No repeat units (no "m m", for instance, but only "m2").
 > 
 > Konrad, can you confirm?

Yes. My goal was to have something much simpler than udunits, given
that Mosaic is meant for a much narrower application domain.

 > Also, I feel like I had to guess a few entries: c (speed of light?), Nav
 > (Avogadro's number?).

All units have been documented in the Mosaic specification for a
while, but I haven't yet put the HTML version on any public server. It
will be on Github Pages, probably before the end of the week.

BTW, you guessed right :-)

 > Is there some kind of "ultimate ASCII SI units definition" available? The xml
 > files from udunits2 seem close to that :-)

It's the best collection I know of.

Konrad.
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Konrad Hinsen
Centre de Biophysique Moléculaire, CNRS Orléans
Synchrotron Soleil - Division Expériences
Saint Aubin - BP 48
91192 Gif sur Yvette Cedex, France
Tel. +33-1 69 35 97 15
E-Mail: research AT khinsen DOT fastmail DOT net
http://dirac.cnrs-orleans.fr/~hinsen/
ORCID: http://orcid.org/0000-0003-0330-9428
Twitter: @khinsen
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