Finite Unitary Reflection Groups
Geoffrey C. Shephard, John A. Todd · Canadian Journal of Mathematics · 1954
Any finite group of linear transformations onnvariables leaves invariant a positive definite Hermitian form, and can therefore be expressed, after a suitable change of variables, as a group of unitary transformations (5, p. 257). Such a group may be thought of as a group of congruent transformations, keeping the origin fixed, in a unitary space Unofndimensions, in which the points are specified by complex vectors withncomponents, and the distance between two points is the norm of the difference between their corresponding vectors.