Upper and lower solutions method for regular singular differential equations with quasi-derivative boundary conditions

In this paper we consider the class of nonlinear singular differential equations of the type-p(x)y′(x)′+q(x)fx,y(x),p(x)y′(x)=0,0

► For nonlinear singular boundary value problems we develop a monotone iterative method.
► For this we use upper and lower solutions which are either ordered or reversely ordered.
► The obtained scheme can be implemented rather easily for constructing solutions of singular boundary value problems.