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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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