[Nexus] unit_cell in NXsample

Wed Sep 17 18:36:31 BST 2014

Hi Folks

Please keep all 6 values together.

The iucr have names for these in cif.

Please use degrees and angstroms - these are conventional!

Cheerio Graeme

(sent from tablet)

On 17 Sep 2014 18:30, Tobias.Richter at diamond.ac.uk wrote:
I not like to pollute the namespace with stuff like "a". unit_cell_a would be a possibility. Having all 6 values under the same umbrella however does have some appeal. We could split the angles and lengths, maybe? 2 umbrellas.

To illustrate my earlier unit idea - this is what I am looking at now:

NX/entry/sample> read unit_cell
  unit_cell[6] (NX_FLOAT64) = [ 5.144700 5.144700 5.144700 ...]
    angle_units = deg
    length_units = angstrom
NX/entry/sample>

An obvious alternative would be to prescribe the units. There are at most two sensible choices for the two units each. Possibly fewer.

Tobias

> -----Original Message-----
> From: NeXus [mailto:nexus-bounces at nexusformat.org] On Behalf Of Pete R.
> Jemian
> Sent: 17 September 2014 18:17
> To: nexus at nexusformat.org
> Subject: Re: [Nexus] unit_cell in NXsample
>
> It would be more sensible to describe each term separately rather than
> rely on this arcane coding of the terms.  If this definition is to be
> revised, I suggest creating fields for each of these terms:
> a
> b
> c
> alpha
> beta
> gamma
>
> Otherwise, we need to relax the units attribute.  A value of "NX_LENGTH
> or NX_NX_ANGLE" (or syntax that can be properly coded in XML) looks
> sensible to the eye but I'm not sure if we have the XML Schema support
> for this.  Yet.  For now, NX_ANY is the only existing value that spans
> what is proper.  An alternative is to introduce a new unit type
> NX_LATTICE_PARAMETER which could be either length or angle.
>
> No good answer for now.
>
> Pete
>
> On 09/17/2014 11:48 AM, Tobias.Richter at diamond.ac.uk wrote:
> > The unit_cell in NXsample is defined like this:
> >
> > <field name="unit_cell" type="NX_FLOAT" units="NX_LENGTH">
> >
> > <doc>Unit cell parameters (lengths and angles)</doc>
> >
> > <dimensions rank="2">
> >
> > <dim index="1" value="n_comp"/>
> >
> > <dim index="2" value="6"/>
> >
> > </dimensions>
> >
> > </field>
> >
> > Since it already says "lengths and angles" the fact that the required
> > units are NX_LENGTH is a bit puzzling. No units for the angles?
> >
> > Would it be sensible to have "length_units" and "angle_units"
> attributes?
> >
> > Tobias
> >
> >
> > --
> >
> > This e-mail and any attachments may contain confidential, copyright
> > and or privileged material, and are for the use of the intended
> > addressee only. If you are not the intended addressee or an
> authorised
> > recipient of the addressee please notify us of receipt by returning
> > the e-mail and do not use, copy, retain, distribute or disclose the
> > information in or attached to the e-mail.
> > Any opinions expressed within this e-mail are those of the individual
> > and not necessarily of Diamond Light Source Ltd.
> > Diamond Light Source Ltd. cannot guarantee that this e-mail or any
> > attachments are free from viruses and we cannot accept liability for
> > any damage which you may sustain as a result of software viruses
> which
> > may be transmitted in or with the message.
> > Diamond Light Source Limited (company no. 4375679). Registered in
> > England and Wales with its registered office at Diamond House,
> Harwell
> > Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United
> > Kingdom
> >
> >
> >
> >
> > _______________________________________________
> > NeXus mailing list
> > NeXus at nexusformat.org
> > http://lists.nexusformat.org/mailman/listinfo/nexus
> >
> _______________________________________________
> NeXus mailing list
> NeXus at nexusformat.org
> http://lists.nexusformat.org/mailman/listinfo/nexus

--
This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail.
Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd.
Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message.
Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom

_______________________________________________
NeXus mailing list
NeXus at nexusformat.org
http://lists.nexusformat.org/mailman/listinfo/nexus

-- 
This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail.
Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. 
Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message.
Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom