Consider the one dimensional heat flow problem. The temperature distribution along a rod of thermal conductivity K is given by a function (-)(.r. f) that obeys the partial differential equation (726)\". f) 1i7()(,ri f) = 0' (7.1": R Dr We assume the initial condition 6(120) = fir)- Let fl.r)='.46(.r u), and find elm. f). 6(.r. I)