Comparison theorems for nonselfadjoint differential equations based on integral inequalities
Comparison theorems for nonselfadjoint differential equations based on integral inequalities
In a variant of the classical Sturmian comparison theorem for selfadjoint Sturm-Liouville equations, A. Ju. Levin has replaced the pointwise conditions on the coefficients by an integral inequality. This theorem is generalized to apply to nonselfadjoint differential equations of the form \[ u'' + b(x)uâ + c(x)u = 0.\]