In mathematics, a polynomial matrix or matrix of polynomials is a matrix whose elements are univariate or multivariate polynomials. Equivalently, a polynomial matrix is a polynomial whose coefficients are matrices. A univariate polynomial matrix P of degree p is defined as: where denotes a matrix of constant coefficients, and is non-zero. An example 3×3 polynomial matrix, degree 2: We can express this by saying that for a ring R, the rings and are isomorphic.