Oscillatory correlations between external force and damping (Q1080687)

Earlier \textit{Chen Qingyi} discussed the problems of ''Oscillatory solutions of reduced wave equation with spherical symmetry''. By using the method of Chen, the classical Sturm theory and the Wentzel-Kramers- Brillouin approximation in quantum mechanics, more general cases are discussed here, that is, the problem of existence of oscillatory solutions and the correlation among damping p(x), the restoring force q(x) and the external force f(x) of the general second-order non- homogeneous linear differential equation \[ y''+p(x)y'+q(x)y=f(x). \]