Evaluating matrix functions for exponential integrators via Carathéodory-Fejér approximation and contour integrals.
Exact asymptotics of nonlinear difference equations with levels and
We study a class of nonlinear difference equations admitting a -Gevrey formal power series solution which, in general, is not - (or Borel-) summable. Using right inverses of an associated difference operator on Banach spaces of so-called quasi-functions, we prove that this formal solution can be lifted to an analytic solution in a suitable domain of the complex plane and show that this analytic solution is an accelero-sum of the formal power series.
Experiment on numerical conformal mapping of unbounded multiply connected domain in fundamental solutions method.
Exponential-type Nagumo norms and summability of formal solutions of singular partial differential equations
In this paper, we study a class of first order nonlinear degenerate partial differential equations with singularity at . Using exponential-type Nagumo norm approach, the Gevrey asymptotic analysis is extended to case of holomorphic parameters in a natural way. A sharp condition is then established to deduce the -summability of the formal solutions. Furthermore, analytical solutions in conical domains are found for each type of these nonlinear singular PDEs.
Extrait d'une Lettre adressée à M. Liouville.
Factorization of rational matrix functions and difference equations
In the beginning of the twentieth century, Plemelj introduced the notion of factorization of matrix functions. The matrix factorization finds applications in many fields such as in the diffraction theory, in the theory of differential equations and in the theory of singular integral operators. However, the explicit formulas for the factors of the factorization are known only in a few classes of matrices. In the present paper we consider a new approach to obtain the factorization of a rational matrix...
Failure of weak holomorphic averaging on multiple connected domains.
Fejér–Riesz factorizations and the structure of bivariate polynomials orthogonal on the bi-circle
We give a complete characterization of the positive trigonometric polynomials on the bi-circle, which can be factored as where is a polynomial nonzero for and . The conditions are in terms of recurrence coefficients associated with the polynomials in lexicographical and reverse lexicographical ordering orthogonal with respect to the weight on the bi-circle. We use this result to describe how specific factorizations of weights on the bi-circle can be translated into identities relating...
Finite-infinite-range inequalities in the complex plane.
Finitely valent locally biholomorphic mappings of multiconnected domains onto the plane.
Fixed points of the derivative and -th power of solutions of complex linear differential equations in the unit disc.
Formes linéaires -adiques
Formules d'interpolation et théorèmes d'unicité pour des fonctions harmoniques de type exponentiel
Formules intégrales pour les formes différentielles de type dans les variétés de Stein
Free interpolation in Hardy-Orlicz spaces
Function Algebras and Flows. III.
Fundamental solutions for Dirac-type operators
We consider the Dirac-type operators D + a, a is a paravector in the Clifford algebra. For this operator we state a Cauchy-Green formula in the spaces and . Further, we consider the Cauchy problem for this operator.
Funktionalgleichungen und Randwertaufgaben
Further convergence results for two quadrature rules for Cauchy type principal value integrals
New convergence and rate-of-convergence results are established for two well-known quadrature rules for the numerical evaluation of Cauchy type principal value integrals along a finite interval, namely the Gauss quadrature rule and a similar interpolatory quadrature rule where the same nodes as in the Gauss rule are used. The main result concerns the convergence of the interpolatory rule for functions satisfying the Hölder condition with exponent less or equal to . The results obtained here supplement...
Ganze Funktionen mit einer vorgeschriebenen asymptotischen Entwicklung.