A complete variational treatment is provided for a family of spiked-harmonicA compact topological proof is presented that the set S = {ψ n } of known exact solutions for α = 2 constitutes an orthonormal basis of the Hilbert space L 2 (0, ∞) .Closed-form expressions are derived for the matrix elements of H with respect to S . These analytical results, and the inclusion of a further free parameter, facilitate optimized variational estimation of the eigenvalues of H to high accuracy.PACS 03.65.Ge Spiked harmonic oscillators . . .