Provide a glimpse of some widely used matrix factorizations, some of which are discussed later in the text.
(Rank Factorization) Suppose an m X n matrix A admits a factorization A = CD where C is m 4 and D is 4 X n.
a. Show that A is the sum of four outer products. (See Section 2.4)
b. Let m = 400 and n = 100. Explain why a computer programmer might prefer to store the data from A in the form of two matrices C and D.