A method of quaternion.

the tangent vector pointing from the reference, the identity by default, to this rotation

Syntax

t = log(rot)

The rotation vector at the identity.

t = log(rot, rotRef)

The tangent vector at a reference.

t = log(rot, rotRef, side='right')

In the frame of the reference’s crystal.

t = log(rot, 'right')

The side alone, at the identity.

Description

The logarithmic map: the vector, of length the rotational angle, whose exponential at the reference gives the rotation. On the left side the vector is that of rot * inv(rotRef), in the specimen’s coordinates; on the right that of inv(rotRef) * rot, in the crystal’s. orientation.log reduces the pair by the symmetry first.

Input

rot rotation
ref rotation, the reference, or ‘left’ or ‘right’ for the side alone

Keywords

keyword default description
side 'left' ‘left’ or ‘right’, the side the tangent vector is taken on

Output

t SO3TangentVector at the reference

See also

quaternion.exp, SO3TangentVector, geodesic

MATLAB’s quaternion.log

source

Citing this page. This page is part of the documentation of MTEX, a free and open source MATLAB toolbox for analyzing and modeling crystallographic textures. It was written by The MTEX Developers and is published at https://mtex-toolbox.github.io/quaternion.log_py.html. If you use MTEX, or reuse text or figures from this page, in your research, please cite

F. Bachmann, R. Hielscher, H. Schaeben: Texture Analysis with MTEX - Free and Open Source Software Toolbox, Solid State Phenomena 160 (2010), 63-68. 10.4028/www.scientific.net/SSP.160.63

BibTeX 
@article{bachmann2010mtex,
  author  = {F. Bachmann and R. Hielscher and H. Schaeben},
  title   = {Texture Analysis with MTEX - Free and Open Source Software Toolbox},
  journal = {Solid State Phenomena},
  volume  = {160},
  pages   = {63-68},
  year    = {2010},
  doi     = {10.4028/www.scientific.net/SSP.160.63},
  url     = {https://doi.org/10.4028/www.scientific.net/SSP.160.63}
}

Other papers describing specific MTEX methods are listed under Publications — please cite the one that best fits your application. The MTEX source code is licensed under the GNU General Public License v2.0; the text and figures of this documentation are licensed under CC BY 4.0, which permits reuse — including by automated systems — provided The MTEX Developers and this page are credited.