[yt-dev] Comment on YTEP-0028: No. of Base Units

Huebl, Axel a.huebl at hzdr.de
Tue May 31 10:05:17 PDT 2016


Hi John,

independent of the dev branch, I am really just referring to the written
proposal in YTEP-0028 as of
  https://ytep.readthedocs.io/en/latest/YTEPs/YTEP-0028.html
.

I was just wondering since it is still "in progress" and we are
implementing the openPMD description right now as a frontend which can
express each quantity as a power to the seven SI base units in a generic
fashion:

  https://git.io/vriio
  example: https://git.io/vrdpA

Sounds great to extent the new UnitSystem a bit further to cover those.
Allowing an additional measure for the angles is actually a nice thing -
I like that, it's quite a common representation problem.


Best,
Axel

On 31.05.2016 15:36, John ZuHone wrote:
> Hi Axel,
> 
> First, I presume you are referring to the new unit system functionality
> in the development branch of yt, correct?
> 
> Currently in yt, "mol" is treated as "dimensionless" and we do not have
> units of candela. I recognize this is different from the SI standard,
> which has them as base units as you mentioned, and actually treats
> angles as dimensionless.
> 
> There are a couple of things going on here:
> 
> 1. Angles are given a dimension since they have an important role in the
> areas of science for which yt was originally tailored to, and it helps
> things from a design perspective to distinguish them from dimensionless
> units.
> 
> 2. The reason for the variance with the SI standard regarding mol and
> candela is somewhat historical as well; yt originally worked only in CGS
> units and even now assumes those as a default units base. The support
> for different unit systems is new. The fact that we treat mol as
> dimensionless and do not have candela is simply because a use case
> requiring otherwise has not presented itself yet.
> 
> Do you have an application of yt that requires a closer adherence to the
> SI standard? If so, we'd be willing to look into making some changes
> along these lines.
> 
> Best,
> 
> John
> 
> 
> ================================
> John ZuHone, Chandra/ACIS Operations
> Harvard-Smithsonian Center for Astrophysics
> 
> 60 Garden St. <x-apple-data-detectors://0>, MS-67       (w) 617-496-1816
> <tel:617-496-1816>
> Cambridge, MA 02138 <x-apple-data-detectors://1/1>.     (m) 781-708-5004
> <tel:781-708-5004>
> 
> john.zuhone at cfa.harvard.edu <mailto:john.zuhone at cfa.harvard.edu>
> http://hea-www.cfa.harvard.edu/~jzuhone
> ================================
> 
> On May 31, 2016, at 9:15 AM, Huebl, Axel <a.huebl at hzdr.de
> <mailto:a.huebl at hzdr.de>> wrote:
> 
>> Dear yt-Developers,
>>
>> we found today that the UnitSytem in YTEP-0028 has only 4 (MKS: 5) base
>> units + the angular measure.
>>
>> This is a bit confusing since the SI unit system has seven base units,
>> further including mol (amount of substance) and candela (luminous
>> intensity), which are not available.
>>
>> Is this intentional?
>>
>>
>> Best,
>> Axel
>>
>> -- 
>>
>> Axel Huebl
>> Phone +49 351 260 3582
>> https://www.hzdr.de/crp
>> Computational Radiation Physics
>> Laser Particle Acceleration Division
>> Helmholtz-Zentrum Dresden - Rossendorf e.V.
>>
>> Bautzner Landstrasse 400, 01328 Dresden
>> POB 510119, D-01314 Dresden
>> Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey
>>          Prof. Dr.Dr.h.c. P. Joehnk
>> VR 1693 beim Amtsgericht Dresden
>>
>> _______________________________________________
>> yt-dev mailing list
>> yt-dev at lists.spacepope.org <mailto:yt-dev at lists.spacepope.org>
>> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
> 
> 
> _______________________________________________
> yt-dev mailing list
> yt-dev at lists.spacepope.org
> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
> 

-- 

Axel Huebl
Phone +49 351 260 3582
https://www.hzdr.de/crp
Computational Radiation Physics
Laser Particle Acceleration Division
Helmholtz-Zentrum Dresden - Rossendorf e.V.

Bautzner Landstrasse 400, 01328 Dresden
POB 510119, D-01314 Dresden
Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey
          Prof. Dr.Dr.h.c. P. Joehnk
VR 1693 beim Amtsgericht Dresden

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 5119 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://lists.spacepope.org/pipermail/yt-dev-spacepope.org/attachments/20160531/6991d965/attachment-0001.bin>


More information about the yt-dev mailing list