[jira] [Closed] (MATH-363) please clarify quaternion conventions in org.apache.commons.math.geometry.Rotation

["Luc Maisonobe (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MATH-363?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Luc Maisonobe closed MATH-363.
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Closing issue as it was included in version 2.2, which has been released

> please clarify quaternion conventions in org.apache.commons.math.geometry.Rotation
> ----------------------------------------------------------------------------------
>
>                 Key: MATH-363
>                 URL: https://issues.apache.org/jira/browse/MATH-363
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 2.0
>         Environment: all
>            Reporter: Albert Huang
>            Priority: Minor
>
> Please clarify which quaternion convention is used in the Rotation documentation, and provide constructor methods to use alternate quaternion conventions.
> For example, the computer graphics community has standardized on representing a rotation of angle theta about the unit vector (i, j, k)  with the quaternion
> { cos(theta/2), i * sin(theta/2), j * sin(theta/2), k * sin(theta/2) }
> e.g., any introductory computer graphics textbook referring to quaternions will describe them in this convention.  This is also the convention appearing on Mathworld, Wikipedia, etc. 
> The convention in org.apache.commons.math.geometry.Rotation instead appears to be
> { cos(-theta/2),  i * sin(-theta/2),  j * sin(-theta/2), k * sin(-theta/2) }
> Since I'm not likely to convince you to switch conventions, please at least document the convention and provide ways to convert from the alternate (this should be trivial?)

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