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On the approximation of isolated eigenvalues of ordinary differential operators. (English) Zbl 1156.34076

The main result of this article (Theorem 2) extends a result of Stolz and Weidmann (Theorem 1) on the approximation of isolated eigenvalues of singular Sturm-Liouville and Dirac operators by the eigenvalues of regular operators.
The definitions of two of the symbols appearing in Formula (4), namely \(\tau_n\) and \(W_a(u, f)\) are not given explicitly. We believe that \(\tau_n\) denotes the differential expression \(\tau\) restricted to the interval \((a_n, b_n)\), while \(W_a(u, f)\) denotes the value of the Wronskian of the functions \(u\) and \(f\) at \(a\).

MSC:

34L40 Particular ordinary differential operators (Dirac, one-dimensional Schrödinger, etc.)
34L16 Numerical approximation of eigenvalues and of other parts of the spectrum of ordinary differential operators
34B20 Weyl theory and its generalizations for ordinary differential equations

References:

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