[cctbxbb] convert an arbitrary point to one inside the asymmetric unit

[Pavel Afonine]

If I understand question correctly, you might be looking for 
map_to_asu(). Search cctbx code for implementation and use examples, 
from which you may infer if that's what you need.

Pavel


On 11/21/16 04:47, Tijskens Engelbert wrote:
> Hi,
>
> I am an experienced C++ and Python programmer, but new to cctbx.
>
> Can any tell me if there is an algorithm in cctbx available  to 
> convert an arbritrary point in direct space to the corresponding point 
> in the asymmetric unit of a given space group? i can figure out how to 
> convert it to the corresponding point in the unit cell at the origin, 
> but from there to the asymmetric unit is unclear to me.
>
> I found the brick class which gives me the assymmetric unit
> from cctbx import crystal,sgtbx
>
> if __name__=='__main__':
>     crystal_symmetry = crystal.symmetry( 
> unit_cell=(3.5093,3.5093,3.5093,90,90,90)
>                                        , space_group_symbol="229" # = 
> "I m -3 m"
>                                        )
>     sg = crystal_symmetry.space_group()
>     brick = sgtbx.brick( sg.type() )
> print brick
>
> I also found cctbx::sgtbx::asu and the classes therein, but they are 
> largely undocumented.
>
> For the interested, this is the problem i want to solve:
> I have a (scalar) physical property P(r), depending on spatial 
> position, presented as a 3D array on a regular grid over the unit cell 
> (space group is known). I need to integrate P(r)*f(r), f(r) being an 
> arbitrary function over a region of direct space, which typically 
> comprises several unit cells. In order to reduce the memory footprint 
> of the P array, i would like to restrict it to the space group’s 
> asymmetric unit.
>
> All help is greatly appreciated.
> kindest regards,
>
> Dr [Engel]bert Tijskens
> HPC Analyst/Consultant
>
> Flemish Supercomputer Centervscentrum.be <http://vscentrum.be>
> HPC core facility CalcUAuantwerp.be/calcua <http://uantwerp.be/calcua>
> Computational mathematicswww.uantwerpen.be/en/rg/cma 
> <http://www.uantwerpen.be/en/rg/cma>
>
> University of Antwerp
> Middelheimlaan1 G.309, B-2020 Antwerp, Belgium
>
> engelbert.tijskens at uantwerpen.be <mailto:engelbert.tijskens at uantwerpen.be>
> ++32 3 265 3879
>
>
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