eigenvalues (or characteristic values)

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1: 28.7 Analytic Continuation of Eigenvalues

§28.7 Analytic Continuation of Eigenvalues

►As functions of $q$, $a_n\left(q\right)$ and $b_n\left(q\right)$ can be continued analytically in the complex $q$-plane. The only singularities are algebraic branch points, with $a_n\left(q\right)$ and $b_n\left(q\right)$ finite at these points. …The normal values are simple roots of the corresponding equations (28.2.21) and (28.2.22). … ► …

2: 29.21 Tables

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Ince (1940a) tabulates the eigenvalues $a_{\nu }^m\left(k^2\right)$, $b_{\nu }^{m+1}\left(k^2\right)$ (with $a_{\nu }^{2m+1}$ and $b_{\nu }^{2m+1}$ interchanged) for $k^2=0.1,0.5,0.9$, $\nu =-\frac{1}{2},0(1)25$, and $m=0,1,2,3$. Precision is 4D.

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Arscott and Khabaza (1962) tabulates the coefficients of the polynomials $P$ in Table 29.12.1 (normalized so that the numerically largest coefficient is unity, i.e. monic polynomials), and the corresponding eigenvalues $h$ for $k^2=0.1(.1)0.9$, $n=1(1)30$. Equations from §29.6 can be used to transform to the normalization adopted in this chapter. Precision is 6S.

3: 29.20 Methods of Computation

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§29.20(i) Lamé Functions

… ►Initial approximations to the eigenvalues can be found, for example, from the asymptotic expansions supplied in §29.7(i). … ►A third method is to approximate eigenvalues and Fourier coefficients of Lamé functions by eigenvalues and eigenvectors of finite matrices using the methods of §§3.2(vi) and 3.8(iv). … ►

§29.20(ii) Lamé Polynomials

►The eigenvalues corresponding to Lamé polynomials are computed from eigenvalues of the finite tridiagonal matrices $𝐌$ given in §29.15(i), using methods described in §3.2(vi) and Ritter (1998). …

4: 29.9 Stability

… ►If $\nu$ is not an integer, then (29.2.1) is unstable iff $h\le a_{\nu }^0\left(k^2\right)$ or $h$ lies in one of the closed intervals with endpoints $a_{\nu }^m\left(k^2\right)$ and $b_{\nu }^m\left(k^2\right)$, $m=1,2,\mathrm{\dots }$. If $\nu$ is a nonnegative integer, then (29.2.1) is unstable iff $h\le a_{\nu }^0\left(k^2\right)$ or $h\in [b_{\nu }^m\left(k^2\right),a_{\nu }^m\left(k^2\right)]$ for some $m=1,2,\mathrm{\dots },\nu$.

5: 28.34 Methods of Computation

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§28.34(ii) Eigenvalues

►Methods for computing the eigenvalues $a_n\left(q\right)$, $b_n\left(q\right)$, and ${\lambda }_{\nu }\left(q\right)$, defined in §§28.2(v) and 28.12(i), include: … ►

Solution of the matrix eigenvalue problem for each of the five infinite matrices that correspond to the linear algebraic equations (28.4.5)–(28.4.8) and (28.14.4). See Zhang and Jin (1996, pp. 479–482) and §3.2(iv).

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Asymptotic approximations by zeros of orthogonal polynomials of increasing degree. See Volkmer (2008). This method also applies to eigenvalues of the Whittaker–Hill equation (§28.31(i)) and eigenvalues of Lamé functions (§29.3(i)).

… ►Also, once the eigenvalues $a_n\left(q\right)$, $b_n\left(q\right)$, and ${\lambda }_{\nu }\left(q\right)$ have been computed the following methods are applicable: …

6: 28.13 Graphics

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§28.13(i) Eigenvalues ${\lambda }_{\nu }\left(q\right)$ for General $\nu$

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Figure 28.13.1: ${\lambda }_{\nu }\left(q\right)$ as a function of $q$ for $\nu =0.5(1)3.5$ and $a_n\left(q\right),b_n\left(q\right)$ for $n=0,1,2,3,4$ ($a$’s), $n=1,2,3,4$ ($b$’s). … Magnify

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Figure 28.13.2: ${\lambda }_{\nu }\left(q\right)$ for , $0\le q\le 10$. Magnify 3D Help

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7: 28.6 Expansions for Small $q$

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§28.6(i) Eigenvalues

►Leading terms of the power series for $a_m\left(q\right)$ and $b_m\left(q\right)$ for $m\le 6$ are: … ►The coefficients of the power series of $a_{2n}\left(q\right)$, $b_{2n}\left(q\right)$ and also $a_{2n+1}\left(q\right)$, $b_{2n+1}\left(q\right)$ are the same until the terms in $q^{2n-2}$ and $q^{2n}$, respectively. … ►Higher coefficients in the foregoing series can be found by equating coefficients in the following continued-fraction equations: … ►Here $j=1$ for $a_{2n}\left(q\right)$, $j=2$ for $b_{2n+2}\left(q\right)$, and $j=3$ for $a_{2n+1}\left(q\right)$ and $b_{2n+1}\left(q\right)$. …

8: 25.17 Physical Applications

§25.17 Physical Applications

►Analogies exist between the distribution of the zeros of $\zeta \left(s\right)$ on the critical line and of semiclassical quantum eigenvalues. This relates to a suggestion of Hilbert and Pólya that the zeros are eigenvalues of some operator, and the Riemann hypothesis is true if that operator is Hermitian. …

9: 29.3 Definitions and Basic Properties

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§29.3(i) Eigenvalues

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§29.3(ii) Distribution

►The eigenvalues interlace according to …The eigenvalues coalesce according to … ►

§29.3(vii) Power Series

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10: 29.4 Graphics

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§29.4(i) Eigenvalues of Lamé’s Equation: Line Graphs

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Figure 29.4.1: $a_{\nu }^m\left(0.5\right)$, $b_{\nu }^{m+1}\left(0.5\right)$ as functions of $\nu$ for $m=0,1,2,3$. Magnify

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Figure 29.4.2: $a_{\nu }^3\left(0.5\right)-b_{\nu }^3\left(0.5\right)$ as a function of $\nu$. Magnify

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§29.4(ii) Eigenvalues of Lamé’s Equation: Surfaces

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Figure 29.4.12: $b_{\nu }^2\left(k^2\right)$ as a function of $\nu$ and $k^2$. Magnify 3D Help

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