 It is called the matrix ring and is denoted by M"n"("R").Given a right "R"-module formula_142, the set of all "R"-linear maps from "U" to itself forms a ring with addition that is of function and multiplication that is of composition of functions; it is called the endomorphism ring of "U" and is denoted by formula_143.As in linear algebra, a matrix ring may be canonically interpreted as an endomorphism ring