Abstract
We derive new inequalities for the eigenvaluesλ k of the Sturm-Liouville problem−u″+qu=λu, u(0)=u(π)=0 under the usual hypothesis thatq has mean value zero. The estimates give upper and lower bounds of the form |λ k −k 2|≤p 1,m k −m+P 2,m k 2m,k 2≥3‖q‖ m ,m=1, 2 where ‖q‖ m is the norm ofq in a Sobolev spaceH m (0, π) and theP's are homogeneous polynomials of degree at most 3 in ‖q‖ m . Such bounds are used in the analysis of the inverse Sturm-Liouville problem.
Zusammenfassung
Für die Eigenwerteλ k des Sturm-Liouville-Problems−u″+qu=λu, u(0)=u(π)=0 werden neue obere und untere Schranken der Form |λ k −k 2|≤p 1,m k −m+P 2,m k 2m,k 2≥3‖q‖ m ,m=1, 2, hergeleitet. Dabei ist ‖q‖ m die Norm vonq im SobolevraumH m(0, π) und dieP sind homogene kubische Polynome in ‖q‖ m . Solche Schranken finden in der Analyse des inversen Sturm-Liouville-Problems Verwendung.
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Marti, J.T. New upper and lower bounds for the eigenvalues of the Sturm-Liouville problem. Computing 42, 239–243 (1989). https://doi.org/10.1007/BF02239751
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DOI: https://doi.org/10.1007/BF02239751