It's just the 2D rotation matrix in complex number form! Prior to quaternions most people saw the complex plane in 2D and simply figured if they wanted to add a third dimension they just had to add ...

Umow (Zeitschrift für physikalische Chemie, 1899, xxx., 711) for demonstrating objectively the rotation of the plane of polarisation of light by an optically active liquid such as a solution of ...

By means of N-body simulations, we investigate if merging is consistent with the observations of subpopulations and rotation in iron-complex GCs. The key parameters are the initial mass and density ...