Quaternions are one of at least two ways to model rotations in a 3D space. Most people are familiar with the classic Euler angles which cover yaw, pitch, and roll.

Etude sur les Quantités mathématiques Grandeurs dirigées, Quaternions Introduction to Quaternions Bibliography of Quaternions and Allied Systems of Mathematics .

THE year 1844 is memorable in the annals of mathematics on account of the first appearance on the printed page of Hamilton's “Quaternions” and Grassmann's “Ausdehnungslehre.” The former ...