Matrix Definition 7.1.1 a11... 41n .. aml ..。amn Note:m x n matrix,square matrix,entry,order,main diagonal,row matrix, column matrix (Tongji University) 3/32Matrix . Definition 7.1.1 . .   a11 . . . a1n . . . . . . am1 . . . amn   Note: m × n matrix, square matrix, entry, order, main diagonal, row matrix, column matrix (Tongji University) Linear Algebra 3 / 32