Let A be a real square matrix. Then det(λ‎I−A) is a polynomial in λ‎ and is called the characteristic polynomial of A. Its degree is equal to order of A. The equation det(λ‎I−A) = 0 is the characteristic equation of A, and its real roots are the eigenvalues of A. These definitions apply equally to square matrices over other fields and to linear maps of finite-dimensional vector spaces. See also Cayley-Hamilton Theorem.