identity matrix
Definition: The identity matrix is a square matrix, the elements on the main diagonal are 1, and the remaining elements are 0. The n-order identity matrix is denoted as I n , for I n , I i,j =0 i≠j , I i,i =1 . The integers in i,j∈[1,n]
nature:
1. An n -dimensional vector v n is multiplied by an n -order identity matrix In, and the result is v n . v n * I n = v n.
2. A matrix Mmn with m rows and n columns is multiplied by the identity matrix In , the result is Mmn . M mn * In = M mn . _
3.In^m=In