Re: [h5md-user] fix remaining imprecisions - particle position

[Pierre de Buyl]

On Fri, Jan 10, 2014 at 03:18:42PM +0100, Felix Höfling wrote:
> Am 10.01.2014, 15:01 Uhr, schrieb Pierre de Buyl
> <address@hidden>:
> 
> >read position
> >if coordinate i is of type 'periodic' and 'image' is present
> >then
> >  compute position_i += image_i*edges_i
> >else
> >  position is fine the way it is
> >end if
> >
> >The modification would be to remove "Otherwise, the data indicate
> >absolute
> >positions in space." Then, the following cases are ok:
> >- periodic position, with no 'image', such as the Monte Carlo
> >mentioned above.
> >- periodic positions, with 'image'
> >- absolute position: as long as there is no 'image' element, you
> >can store
> >  absolute positions even if the boundary is periodic.
> >
> >Olaf, does that reply to your query about the MSD?
> >
> 
> Basically, what your scheme above states is "Otherwise, the position data
> are fine the way they are." How shall we phrase it in a concise and less
> familiar way?
> 
> To me, "absolute position" means that the data do not need further
> adjustment, which is precisely what you're saying. I wouldn't drop the
> sentence to also specify what is meant if image is absent.

Ok, it does look equivalent actually :-)

Then, maybe one would need to clarify that 'image' is only to be used in those
directions that specify 'periodic' for the boundary? (i.e. a wall in z but PBC
in x and y)? 'image' would be zero any in direction z then so the interpretation
of the file does not change.