4. For n = 50, 100, 200, 300, 400, do the following. Let A be
the n × n matrix with entacries Aij = p 2(i − j) 2 + n/5. Define
xexact = [1, 1, . . . , 1]T , and then compute b = Axexact. Using
Matlab’s backslash, numerically solve the equation
Ax = b,
thereby producing a computed solution xc. In exact arithmetic xc
= xexact of course, but in IEEE double precision xc will not...