rapsod

I need only algoritam how too break this equation so I can solve it with runge-kutte metod. I forget to say that y=y(x). The sin(y + h(x)) is problem. It is not a polinom but... maybe I can transform it in sum so sin become a polinome. PLEASE HELP!!! MY BRAIN HURTS ME!!!

Can somebody tell me what type is this differential equation: y''-f(x)y'-sin(y + h(x))=0 I am interested more at numerical solution.