Re: [ccp4bb] Rotation axis

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

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Subject: Re: D-Amino acids to L-Amino acids
From: Artem Evdokimov artem {- at -} XTALS {- dot -} ORG
Date: 2008-08-02

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Subject: Re: D-Amino acids to L-Amino acids
From: Paul Emsley paul {- dot -} emsley {- at -} BIOCH {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2008-08-03

Subject: Re: Rotation axis
From: "Winn, MD (Martyn)" m {- dot -} d {- dot -} winn {- at -} DL {- dot -} AC {- dot -} UK
Date: 2008-08-03

ROTMAT will also do this. But I am not sure that this is what Phil wants?

The superposition transformation includes a translation, so there is no
locus of points that are left unchanged. You can generate an axis of
rotation for polar angles from the R which will be quite different from t.
You should be able to translate the rotation axis (change the origin of
the coordinate system) to get a new transformation x' = R'x + t' which
might be better for visualisation. If Phil's last sentence is right, you
should be able to arrange it so that t' is parallel to the rotation axis
of R'

No, I don't know how to do this off the top of my head, but it sounds
very similar to the transformations done in the Schomaker and Trueblood
TLS paper.

Or maybe this is over-complicating things ;-)

Martyn

-----Original Message-----
From: CCP4 bulletin board on behalf of Herman.Schreuder@SANOFI-AVENTIS.COM
Sent: Tue 7/29/2008 1:32 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] Rotation axis

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:CCP4BB@JISCMAIL.AC.UK] On Behalf Of
Phil Evans
Sent: Tuesday, July 29, 2008 10:11 AM
To: CCP4BB@JISCMAIL.AC.UK
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

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: D-Amino acids to L-Amino acids
From: Artem Evdokimov artem {- at -} XTALS {- dot -} ORG
Date: 2008-08-02

Next message:
Subject: Re: D-Amino acids to L-Amino acids
From: Paul Emsley paul {- dot -} emsley {- at -} BIOCH {- dot -} OX {- dot -} AC {- dot -} UK
Date: 2008-08-03