1. The problem statement, all variables and given/known data Solve from the differential equation below numerically for the function [itex] \phi(x) [/itex] for [itex] x \in [0,L] [/itex] [tex]\phi '' (x) + D(x) sin(\phi (x) ) + E sin(\phi (x) ) cos( \phi (x) ) = 0 [/tex] with D(x) a polynomial. 2. Relevant equations Matlab. 3. The attempt at a solution I can rewrite it in a state space form and then iterate towards the function [itex] \phi(x) [/itex] if D is constant. But what can I do with that pesky D(x). If I am iterating towards D(x) I cannot iterate, right?