1,216 research outputs found
Efficient computation of high index Sturm-Liouville eigenvalues for problems in physics
Finding the eigenvalues of a Sturm-Liouville problem can be a computationally
challenging task, especially when a large set of eigenvalues is computed, or
just when particularly large eigenvalues are sought. This is a consequence of
the highly oscillatory behaviour of the solutions corresponding to high
eigenvalues, which forces a naive integrator to take increasingly smaller
steps. We will discuss some techniques that yield uniform approximation over
the whole eigenvalue spectrum and can take large steps even for high
eigenvalues. In particular, we will focus on methods based on coefficient
approximation which replace the coefficient functions of the Sturm-Liouville
problem by simpler approximations and then solve the approximating problem. The
use of (modified) Magnus or Neumann integrators allows to extend the
coefficient approximation idea to higher order methods
A Finite Element Method for the Fractional Sturm-Liouville Problem
In this work, we propose an efficient finite element method for solving
fractional Sturm-Liouville problems involving either the Caputo or
Riemann-Liouville derivative of order on the unit interval
. It is based on novel variational formulations of the eigenvalue
problem. Error estimates are provided for the finite element approximations of
the eigenvalues. Numerical results are presented to illustrate the efficiency
and accuracy of the method. The results indicate that the method can achieve a
second-order convergence for both fractional derivatives, and can provide
accurate approximations to multiple eigenvalues simultaneously.Comment: 30 pages, 7 figure
Automatic computation of quantum-mechanical bound states and wavefunctions
We discuss the automatic solution of the multichannel Schr\"odinger equation.
The proposed approach is based on the use of a CP method for which the step
size is not restricted by the oscillations in the solution. Moreover, this CP
method turns out to form a natural scheme for the integration of the Riccati
differential equation which arises when introducing the (inverse) logarithmic
derivative. A new Pr\"ufer type mechanism which derives all the required
information from the propagation of the inverse of the log-derivative, is
introduced. It improves and refines the eigenvalue shooting process and implies
that the user may specify the required eigenvalue by its index
Classical and vector sturm—liouville problems: recent advances in singular-point analysis and shooting-type algorithms
AbstractSignificant advances have been made in the last year or two in algorithms and theory for Sturm—Liouville problems (SLPs). For the classical regular or singular SLP −(p(x)u′)′ + q(x)u = λw(x)u, a < x < b, we outline the algorithmic approaches of the recent library codes and what they can now routinely achieve.For a library code, automatic treatment of singular problems is a must. New results are presented which clarify the effect of various numerical methods of handling a singular endpoint.For the vector generalization −(P(x)u′)′+Q(x)u = λW(x)u where now u is a vector function of x, and P, Q, W are matrices, and for the corresponding higher-order vector self-adjoint problem, we outline the equally impressive advances in algorithms and theory
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