DEFINITION4 Matrices 矩阵 Let a be an m x k matrix and b be a k x n matrix The product of A and B, denoted by ab, is the m X n matrix with (i, jth entry equal to the sum of the products of the corresponding elements from the ith row of a and the jth column of B In ab=cil, then 可=a1b1+ab2+…,+akbkM a t r i c e s 矩 阵 DEFINITION 4. Let A be an m × k matrix and B be a k × n matrix. The product of A and B, denoted by AB, is the m × n matrix with (i, j)th entry equal to the sum of the products of the corresponding elements from the ith row of A and the jth column of B. In AB = [cij], then Cij = ai1b1j + ai2b2j + … + aikbkj =