C3.3 is a computer exmaple from the book Linear Signals and Systems. Type in "computer example C3.3" in the search bar in the pdf version of the book and you should be able to locate the example. Page 186.

Given the following difference equation: y[n + 2] - y[n] = x[n + 2] + x[n] with initial conditions y[-1] = 1, y[-2] = 1/2 and x[n] = nu[n] (a) Find the solution of the difference equation analyatically (b) Use matlab to sketch the answer of part (a) (c) Use iterative method in matlab to solve the equation "C3.3" (d) Compare the answer of both parts in (a) and (c)