A note on asymptotics and nonoscillation of linear $q$-difference equations

Abstract

We study the linear second order $q$-difference equation $y(q^2t)+a(t)y(qt)+b(t)y(t)=0$ on the $q$-uniform lattice $\{q^k:k\in\mathbb{N}_0\}$ with $q>1$, where $b(t)\ne0$. We establish various conditions guaranteeing the existence of solutions satisfying certain estimates resp. (non)oscillation of all solutions resp. $q$-regular boundedness of solutions resp. $q$-regular variation of solutions. Such results may provide quite precise information about their asymptotic behavior. Some of our results generalize existing Kneser type criteria and asymptotic formulas, which were stated for the equation $D_q^2y(qt)+p(t)y(qt)=0$, $D_q$ being the Jackson derivative. In the proofs however we use an original approach.

Keywords

• $q$-difference equation
• oscillation
• asymptotic behavior
• regular variation