Pierre de Buyl writes:
> Some people work with [-L/2:L/2], others with [0:L].
>
> offset is there so that users may dump their position data without
> operation between memory and file, whatever box convention they use.
Do I conclude then that "offset" is supposed to be -L/2 in the first
case, and 0 in the second?
Olaf Lenz writes:
> I was always wondering about the offset, but I didn't want to start
that
> discussion. Thanks, Konrad. :-/
>
> The offset is mathematically irrelevant.
I agree.
> I also do not see what the offset is needed for in the file.
I'd look at this from a different point of view: if it's there, what
information does it convey? What conclusion can a trajectory reader
draw from it?
> The only case that I can think of where the offset might be useful is,
> when it is somehow guaranteed that the positions are all within the
> primary image that is defined by the offset and the edges.
Exactly.
> Therefore, from my point of view, the offset is useless and can be
> removed from the specs.
Or add a guarantee about the positions being in the primary image to
the specs. From my experience, that can be useful information to have.
Konrad.