Quaternion: Difference between revisions

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==Double Quaternions==
==Double Quaternions==
Note that double quaternions are different from dual quaternions.   
Note that double quaternions are different from dual quaternions.   
Double quaternions are written as <math>q_1 + \epsilon q_2</math> with <math>\epsilon^2 = 1</math> and applied to a quaternion <math>p</math> representing a point as <math>q_1 p q_2</math>.   
Double quaternions are written as <math>q_1 + \epsilon q_2</math> with <math>\epsilon^2 = 1</math> and applied to a quaternion <math>p</math> representing a point as <math>q_1 p \bar{q}_2</math>.   
Dual quaternions are written as <math>q_1 + \varepsilon q_2</math> with <math>\varepsilon^2 = 0</math> and applied to a dual quaternion <math>p</math> representing a point as <math>(q_1 + \varepsilon q_2) p (\bar{q}_1 + \varepsilon \bar{q}_2)</math>  
Dual quaternions are written as <math>q_1 + \varepsilon q_2</math> with <math>\varepsilon^2 = 0</math> and applied to a dual quaternion <math>p</math> representing a point as <math>(q_1 + \varepsilon q_2) p (\bar{q}_1 + \varepsilon \bar{q}_2)</math>