quaternion

n.

四个一组，四人一组，四元数；

1. The norm of a quaternion is similar to that of a vector.
   四元数的平均值与矢量的有点相似。
2. This paper studies comparatively dual Euler method and quaternion method which are used for the solution of the singularity of the Euler equation.
   对解决欧拉方程奇异性的双欧法和四元数法进行了对比研究。

Quaternion and Matrices of Quaternions
A quaternion-based adaptive attitude tracking controller without velocity measurements
Statistical Ensembles of Complex, Quaternion, and Real Matrices
Quaternion-based extended Kalman filter for determining orientation by inertial and magnetic sensing
An extended Kalman filter for quaternion-based orientation estimation using MARG sensors
Spatio-temporal Saliency detection using phase spectrum of quaternion fourier transform
Spatio-temporal Saliency detection using phase spectrum of quaternion fourier transform
Implementation and Experimental Results of a Quaternion-Based Kalman Filter for Human Body Motion Tracking
A comparison of unscented and extended Kalman filtering for estimating quaternion motion
Design, Implementation, and Experimental Results of a Quaternion-Based Kalman Filter for Human Body Motion Tracking