3. For upper triangular matrices A, B Rnxn, we can have better (i.e. smaller) flop count for computing matrix product C=AB by only considering nonzero elements. (a) Write a summation expression of C;; that includes only nonzero elements of A and B. (b) Based on this expression, write a pseudocode to compute the matrix product. (c) Estimate the number of flops the algorithm requires and compare it with the flop count required for the general case. Hint: These formulas are useful when determining the flop count: n i: i=1 n n(n+1) [: 2 i=1 n(n+1)(n+2) 6 = (3)