Matrices

Let m,n be positive integers. An m×n matrix is a rectangular array A = ( a 11 a 12 … a 1 n a 21 a 22 … a 2 n ⋮ ⋮ ⋮ a m 1 a m 2 … a m n ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203748961/aca0116a-0c65-455a-ab7c-0f2ab0e9f704/content/eq41.tif"/>