Dear Phil,
Because question keep popping up in the bullitin board about conversion
from a rotation matrix into rotation angles, I decided to take the
relevant subroutines from an old program from Groningen and make a jiffy
to do these conversions. It is a small fortran program and does not need
any additional libraries or subroutines. The program will take a
rotation matrix and translation vector and print all kind of rotation
angles and also the component of the translation vector parallel to the
rotation axis, which is the number you want. All other components of the
translation vector can be made zero by choosing the right position of
the rotation axis.
Best regards,
Herman Schreuder
-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of
Phil Evans
Sent: Tuesday, July 29, 2008 10:11 AM
To: [log in to unmask]
Subject: [ccp4bb] Rotation axis
If I've go a superposition transformation (x' = Rx + t), as it happens
from a superposition in ccp4mg, how do I get the position & direction of
the rotation axis (to draw in a picture)?
I know that any (orthonormal) transformation can be represented as a
rotation about an axis + a screw translation along that axis
I'm sure I've done this before ...
thanks
Phil
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