Direction Cosines - How are they defined?

[Peter Fuhrmann]

Hallo,
I'm interested in handling the anisotropic extinction using the program 
MOLLY. Therefor I need the direction cosines (6 values), which desribe 
the incident and reflected beam whith respect to the crystal orientation.
The orienting matrix, hkl and diffractometer geometry are known.
Does anybody know about this topic and can tell me, how these values are 
defined, or where I can find some hints in the litrature?

Thanks, Peter.


Peter Fuhrmann -  <fuhrmann at chemie.fu-berlin.de>  - Tel.: +49-30-8383408    
FU Berlin - Institut fuer Kristallographie - Takustr. 6 - D-14195 Berlin
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Peter Fuhrmann -  <fuhrmann at chemie.fu-berlin.de>  - Tel.: +49-30-8383408    
FU Berlin - Institut fuer Kristallographie - Takustr. 6 - D-14195 Berlin