Solution
= Solution
Write the energy form as $Q[\psi]=\int_\alpha^\beta(p|\psi'|^2+q|\psi|^2)dx$ and the weighted squared norm as $N[\psi]=\int_\alpha^\beta w|\psi|^2dx$. For real coefficients and appropriate homogeneous boundary conditions, the <Sturm-Liouville problem> is the stationary-point equation for their <Rayleigh quotient> $Q/N$.