4. The product y = Ax of an m × n matrix A times a vector x =
(x1, x2, . . . , xn) T can be computed row-wise as y = [A(1,:)*x;
A(2,:)*x; ... ;A(m,:)*x]; that is y(1) = A(1,:)*x y(2) = A(2,:)*x
... y(m) = A(m,:)*x Write a function M-file that takes as input a
matrix A and a vector x, and as output gives the product y = Ax by
row, as defined above (Hint: use...