unknown function f(n) satisfies: af - nf' = f", f(0) = 1, f +0 as n oo. %3D With a = 0 this is the Rayleigh problem. Show that in this case the solution is f(n) = 1- erf where the error function is defined by 2 erf(r) = exp(-t) dt. Also find a solution for the case a = : Hint: Try f(n) ~ n as a first soln, and then find a second solution using the first.