[cctbxbb] using scatterer flags?
pafonine at lbl.gov
Tue Apr 16 10:50:10 PDT 2013
I added "use" flag (at the time when I was adding all other scatterer
flags) rather as a placeholder for a future use, so yes, indeed,
currently it is not respected in fcalc and gradients calculation (though
it should be respected!). Perhaps it's time to start using it...
On 4/15/13 11:58 AM, Richard Gildea wrote:
> Are the same scatterers contributing to f_calc for every calculation,
> or will the scatterers that are contributing vary from calculation to
> calculation? In the case of the former it might be simplest to create
> a new copy of the xray_structure with only those scatterers.
> It looks the "use" flag isn't actually respected in the structure
> factor or gradient calculations as far as I can tell. If you feel you
> need something like this rather than creating new copies of the
> xray_structure with only the scatterers you need or alternatively
> setting the occupancy to zero, then this is probably something we can
> add into the code. There is some code in cctbx/xray/scatterer_flags.h
> for flags_set_grad_*() that will set a selection of gradients all at
> once in C++, but I don't see an equivalent for set_use_*(). I suspect
> that the overhead of looping through the scatterers to set flags in
> Python would be small compared to the cost of calculating the
> structure factors in the first place.
> On 15 April 2013 10:40, Jan Marten Simons <marten at xtal.rwth-aachen.de
> <mailto:marten at xtal.rwth-aachen.de>> wrote:
> Am Montag 15 April 2013 18:33:00 schrieb Jan Marten Simons:
> > Hi,
> > while working on a really fast way to calculate the structure
> factors of a
> > few millions of different modifications of a structure with only the
> > selected scatterers contributing to f_calc ....
> > (I think building a larger structure and working with
> > selections might be faster than creating lots of different
> > containing only the desired scatterers, but I might be wrong on
> I've found "flags" might be what I'm looking for. So if I could
> set the "use"
> flag for all scatterers at once and if it was taken into
> consideration during
> structure factor calculation then I think it would most likely be
> the fastest
> way to enable or disable the contribution of individual scatterers
> to the
> structure factors. Am I right on this and how would I best
> interface with the
> flags mechanism (from python)?
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