A Uniformly Convergent Difference Scheme for a Semilinear Singular Perturbation Problem.
We consider a discrete Schrödinger operator 𝒥 with Wigner-von Neumann potential not belonging to l². We find the asymptotics of orthonormal polynomials associated to 𝒥. We prove a Weyl-Titchmarsh type formula, which relates the spectral density of 𝒥 to a coefficient in the asymptotics of the orthonormal polynomials.
Small perturbations of an equilibrium plasma satisfy the linearized magnetohydrodynamics equations. These form a mixed elliptic-hyperbolic system that in a straight-field geometry and for a fixed time frequency may be reduced to a single scalar equation div, where may have singularities in the domaind of definition. We study the case when is a half-plane and possesses high Fourier components, analyzing the changes brought about by the singularity . We show that absorptions of energy takes...
The maximal operator S⁎ for the spherical summation operator (or disc multiplier) associated with the Jacobi transform through the defining relation for a function f on ℝ is shown to be bounded from into for (4α + 4)/(2α + 3) < p ≤ 2. Moreover S⁎ is bounded from into . In particular converges almost everywhere towards f, for , whenever (4α + 4)/(2α + 3) < p ≤ 2.
We provide an elementary proof of the asymptotic behavior of solutions of second order differential equations without successive approximation argument.
We give a proof of the fact that any holomorphic Pfaffian form in two variables has a convergent integral curve. The proof gives an effective method to construct the solution, and we extend it to get a Gevrey type solution for a Gevrey form.
Here we present basic ideas and algorithms of Power Geometry and give a survey of some of its applications. In Section 2, we consider one generic ordinary differential equation and demonstrate how to find asymptotic forms and asymptotic expansions of its solutions. In Section 3, we demonstrate how to find expansions of solutions to Painlevé equations by this method, and we analyze singularities of plane oscillations of a satellite on an elliptic orbit. In Section 4, we consider the problem of local...