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Several new formulas are developed that enable the evaluation of a family of definite integrals containing the product of two Whittaker W-functions. The integration is performed with respect to the second index, and the first index is…

Mathematical Physics · Physics 2015-06-26 Peter A. Becker

Two approximations of the integral of a class of sinusoidal composite functions, for which an explicit form does not exist, are derived. Numerical experiments show that the proposed approximations yield an error that does not depend on the…

Numerical Analysis · Mathematics 2024-01-17 Alberto Costa

We consider the connection of functional decompositions of rational functions over the real and complex numbers, and a question about curves on a Riemann sphere which are invariant under a rational function.

Complex Variables · Mathematics 2024-02-23 Peter Müller

In this paper, we introduce new classes of functions that extend the known classes of functions of complex variable, such as entire functions, meromorphic functions, rational functions and polynomial functions and take values in the set of…

Classical Analysis and ODEs · Mathematics 2025-08-14 Vyacheslav M. Abramov

Two possible realizations of the formal neuron are considered as quantum system. The first type complies with classical system. The second type vastly increases the possible problems.

General Physics · Physics 2007-05-23 S. V. Belim , S. Yu. Belim

We describe an algorithm to decompose rational functions from which we determine the poset of groups fixing these functions.

Number Theory · Mathematics 2008-08-21 John McKay , David Sevilla

We explore how to compute, classically at strong coupling, correlation functions of local operators corresponding to classical spinning string states. The picture we obtain is of `fattened' Witten diagrams, the evaluation of which turns out…

High Energy Physics - Theory · Physics 2014-11-20 Romuald A. Janik , Piotr Surowka , Andrzej Wereszczynski

We analyze certain compositions of rational inner functions in the unit polydisk $\mathbb{D}^{d}$ with polydegree $(n,1)$, $n\in \mathbb{N}^{d-1}$, and isolated singularities in $\mathbb{T}^d$. Provided an irreducibility condition is met,…

Complex Variables · Mathematics 2023-02-02 Alan Sola

Algorithms for computing rational generating functions of solutions of one-dimensional difference equations are well-known and easy to implement. We propose an algorithm for computing rational generating functions of solutions of…

Combinatorics · Mathematics 2019-11-05 Alexey A. Kytmanov , Alexander P. Lyapin , Timur M. Sadykov

We define two classes of functions, called regular (respectively, first-order) list functions, which manipulate objects such as lists, lists of lists, pairs of lists, lists of pairs of lists, etc. The definition is in the style of regular…

Formal Languages and Automata Theory · Computer Science 2018-03-19 Mikolaj Bojanczyk , Laure Daviaud , Krishna Shankara Narayanan

We describe a first attempt to calculate scalar 2-loop box-functions with arbitrary internal masses, applying a novel method proposed in hep-ph/9407234. Four of the eight integrals are accessible to integration by means of the residue…

High Energy Physics - Phenomenology · Physics 2011-09-13 R. Kreckel , D. Kreimer , K. Schilcher

We develop contractive finite dimensional realizations for rational matrix functions of one variable on domains that are not simply connected, such as the annulus. The proof uses multivariable contractive realization results as well as…

Functional Analysis · Mathematics 2025-04-07 Radomił Baran , Piotr Pikul , Hugo J. Woerdeman , Michał Wojtylak

We introduce certain linear positive operators and study some approximation properties of these operators in the space of functions, continuous on a compact set, of two variables. We also find the order of this approximation by using…

Classical Analysis and ODEs · Mathematics 2007-09-24 Fatma Tasdelen , Ali Olgun , Gulen Bascanbaz-Tunca

In this paper we generalize classical results regarding minimal realizations of non-commutative (nc) rational functions using nc Fornasini-Marchesini realizations which are centred at an arbitrary matrix point. We prove the existence and…

Functional Analysis · Mathematics 2021-09-17 Motke Porat , Victor Vinnikov

This essay contains three parts. The first part of essay focuses on the hypothesis of the functional semantic constructions (FSC-Hypothesis). This hypothesis explains that a language, a number, a money are the functional semantic…

History and Overview · Mathematics 2007-05-23 Y. Semenov

We consider integration of functions with values in a partially ordered vector space, and two notions of extension of the space of integrable functions. Applying both extensions to the space of real valued simple functions on a measure…

Functional Analysis · Mathematics 2021-10-18 Arnoud van Rooij , Willem van Zuijlen

We present criteria for deciding whether a bivariate rational function in two variables can be written as a sum of two (q-)differences of bivariate rational functions. Using these criteria, we show how certain double sums can be evaluated,…

Combinatorics · Mathematics 2012-10-25 Shaoshi Chen , Michael F. Singer

Properties of the mappings \begin{align*} C&\mapsto\frac1{(2\pi i)^2}\int_{\Gamma_1}\int_{\Gamma_2}f(\lambda,\mu)\,R_{1,\,\lambda}\,C\, R_{2,\,\mu}\,d\mu\,d\lambda, C&\mapsto\frac1{2\pi i}\int_{\Gamma}g(\lambda)R_{1,\,\lambda}\,C\,…

Functional Analysis · Mathematics 2016-04-27 V. G. Kurbatov , I. V. Kurbatova , M. N. Oreshina

We give an elementary characterization of rational functions among meromorphic functions in the complex plane.

Complex Variables · Mathematics 2017-12-13 Bao Qin Li

A natural kind of compactification of the virtual moduli spaces of rational functions of one complex variable is given. To describe the boundary points geometrically, the authors introduce the concept of rational functions with nodes,…

Complex Variables · Mathematics 2016-02-16 Masayo Fujimura , Masahiko Taniguchi