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Re: [IMP-dev] too many rotations in IMP




doc updated. Nothing invented : usual zyz convention

2009/5/7 Daniel Russel <">>
But I need a better description of what you need as there are a variety of varients of zyz depending on which rotations are done with a body frame axis and which are fixed. If you fill in the docs on the rotation_from function then it will be clearer. Thanks.



On May 7, 2009, at 3:32 PM, Javier Ángel Velázquez Muriel <" target="_blank">> wrote:

I'm not that unreasonable, or at least I like to think that. I can accept the quaternions.
Can somebody please add then a function to come back from a rotation3D to a set of angles?

After finding a good rotation I need to spit to the stupid user (i.e., me) the proper angles, because that is what everybody uses de facto in the field. Help!

2009/5/7 Ben Webb <" target="_blank">" target="_blank">>
Javier Ángel Velázquez Muriel wrote:
> If I remember correctly, I said that I *****NEED***** and prefer the 3
> euler angles to be specified for project(). Therefore the new version of
> project is not helpful, and I am going to go back to the version that
> satisfied my needs. I can always document everything as much as needed.

The best way to ensure that something you need works is to write a test
case for it. Then anybody that changes it will break your test, and we
can all yell at them.

There are several people that can help you (myself included) to work
with Rotation3D. But it doesn't make sense to have other classes to work
with rotations, since nobody will know which is the "right" one and it
is harder to test multiple code paths. And it's pretty much universally
acknowledged these days that if you really *have* to choose one way of
representing a rotation, three Euler angles is most definitely not the
way to do it (gimbal lock and the order of the angles being the most
obvious problems).

       Ben
--
" target="_blank">" target="_blank">                      http://salilab.org/~ben/
"It is a capital mistake to theorize before one has data."
       - Sir Arthur Conan Doyle


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