[ 源代码： cqrlib ]
软件包：libcqrlib2（1.1.4-3 以及其他的）
Library for quaternion arithmetic and rotation math
Quaternions are four-dimensional numbers which form an associative normed division algebra over the real numbers. Unit quaternions are a convenient and efficient way to represent orientations and rotations in three dimensions.
CQRlib is an ANSI C implementation of a utility library for quaternion arithmetic and quaternion rotation math.