交错级数的对数判别法

从正项级数的Raabe对数判别法入手,给出了交错级数的一个新的审敛方法.与文[1],[2]所给的审敛法相比,当交错级数的一般项含有幂指项时,利用该审敛法判断其敛散性显得尤为简便.     

On certain relations between the maximum modulus and the maximal term of an entire dirichlet series

For an entire Dirichlet series , sufficient conditions on the exponents are established such that the following relations hold outside a set of finite measure asx→+∞:

On new third-order convergent iterative formulas

In this paper, we present new iteration methods with cubic convergence for solving nonlinear equations. The main advantage of the new methods are free from second derivatives and it permit that the first derivative is zero in some points. Analysis of efficiency shows that the new methods can compete with Newton’s method and the classical third-order methods. Numerical results indicate that the new methods are effective and have definite practical utility.      

The Exceptional Set in the Two Prime Squares and a Prime Problem

In this paper we prove that, with at most O（N^5/12＋ε） exceptions, all positive odd integers n ≤ N with n ≡ 0 or 1（mod 3） can be written as a sum of a prime and two squares of primes.     

Rearrangement of conditionally convergent series on a small set

We consider ideals I of subsets of the set of natural numbers such that for every conditionally convergent series _∑n∈ωan and every there is a permutation such that _∑n∈ωaπr(n)=r and

     

Beurling algebra analogues of the classical theorems of Wiener and Lévy on absolutely convergent fourier series

Letf be a continuous function on the unit circle Γ, whose Fourier series is ω-absolutely convergent for some weight ω on the set of integersZ. If f is nowhere vanishing on Γ, then there exists a weightv onZ such that 1/f hadv-absolutely convergent Fourier series. This includes Wiener’s classical theorem. As a corollary, it follows that if φ is holomorphic on a neighbourhood of the range off, then there exists a weight Χ on Z such that φ ◯f has Χ-absolutely convergent Fourier series. This is a weighted analogue of Lévy’s generalization of Wiener’s theorem. In the theorems,v and Χ are non-constant if and only if ω is non-constant. In general, the results fail ifv or Χ is required to be the same weight ω.     

On a class of inequalities for orthonormal systems

In this paper, a novel approach to the proof of inequalities of Lieb-Thirring type based on the standard apparatus of the theory of orthogonal series is proposed.     

On the set of all continuous functions with uniformly convergent Fourier series

In this article we calculate the exact location in the Borel hierarchy of the set of all continuous functions on the unit circle with uniformly convergent Fourier series. It turns out to be complete Also we prove that any set that includes must contain a continuous function with divergent Fourier series.

     

New rapidly convergent series representations for

We give three series representations for the values of the Riemann zeta function at positive odd integers. One representation extends Ewell's result for [Amer. Math. Monthly 97 (1990), 219-220] and is considerably simpler than the two generalisations proposed earlier. The second representation is even simpler:

where the coefficients for a fixed are rational in and are explicitly given by the finite sum involving the Bernoulli numbers. The third representation is obtained from the second by the Kummer transformation. We demonstrate the rapid convergence of this series using several examples.

     

A note on the summation of slowly convergent alternating series

Thekth term of the infinite series is larger than 0.5 wheneverk <k ₀, wherek ₀ + 1 =e ¹⁰²⁴. To sum this series correct to order 10^–1 using direct summation seems an impossible task, notwithstanding the power of modern computers. This note will present an alternative approach to those classical methods (the Euler transformation is one) which can accurately sum such series. The theory to be presented has the added advantage of providing accurate bounds for the error in the approximate result. The method used will be Euler-Maclaurin summation, revitalised by computer algebra.The sum of theintegrated series asx 0.     

The differentiation operator in the space of uniformly convergent Dirichlet series

Continuity, compactness, the spectrum and ergodic properties of the differentiation operator are investigated, when it acts in the Fréchet space of all Dirichlet series that are uniformly convergent in all half-planes for each . The properties of the formal inverse of the differentiation are also investigated.     

On the absolute convergence of multiple fourier series

Let f: R ^N → C be a periodic function with period 2π in each variable. We prove suffcient conditions for the absolute convergence of the multiple Fourier series of f in terms of moduli of continuity, of bounded variation in the sense of Vitali or Hardy and Krause, and of the mixed partial derivative in case f is an absolutely continuous function. Our results extend the classical theorems of Bernstein and Zygmund from single to multiple Fourier series. This research was started while the first author was a visiting professor at the Department of Mathematics, Texas A&M University, College Station during the fall semester in 2005; and it was also supported by the Hungarian National Foundation for Scientific Research under Grant T 046 192.     

On a certain class of dirichlet series

For 0 1, let L(s,a) and L?(s,a) be the Dirichlet series L(s,a) = ∑ : cos (2πna)n^-s and L? [001](s,a) = ∑ sin (2πna)n^-s. We show that L(s,a) and L?(s,a[001]) have holomorphic extension in the whole complex plane. Values of L(s,a)andL?(s,a) at the negative integers are given. Moreover values of L?(s,a) at the intergers 0,2,4,... and values of L^?(s,a)at the integers 1,3,5,... are obtained. An exponential sums of certain recursion formulas are obtained by means of bernoulli numbers and Bernoulli polynomials     

Spaces of vector-valued Dirichlet series in a half plane

Dirichlet series with real frequencies which represent entire functions on the complex plane C have been investigated by many authors. Several properties such as topological structures, linear continuous functionals, and bases have been considered. Le Hai Khoi derived some results with Dirichlet series having negative real frequencies which represent holomorphic functions in a half plane. In the present paper, we have obtained some properties of holomorphic Dirichlet series having positive exponents, whose coefficients belong to a Banach algebra.     

Riemann's Fragment on Limit Values of Elliptic Modular Functions

We give an interpretation different from that of Dedekind to work n° 28 of the complete works of Riemann Fragmente über die Grenzfälle der Elliptischen Modulfunctionen.We prove a theorem of inversion of radial limit and sum in a series of functions. This allows us to justify all of Riemann's reasoning in the fragment to obtain the limit values of modular elliptic functions. In particular we prove the statement of Riemann that for every rational number x we have where denotes the periodic function with period 1, such that (x) = x when |x| < 1/2, and (n + ) = 0 for every n Z.This assertion of Riemann was criticized by Dedekind. We also give the transformation formulae of the logarithms of the classical theta-function ₃(0), giving an alternative form to that obtained by B. C. Berndt [1].     

On series containing products of Legendre polynomials

Explicit formulas are established for infinite sums of products of three or four Legendre polynomials of nth order with coefficients 2n + 1; the series depends only the arguments of the polynomials and contains no other variables. We show that, for the product of three polynomials, the sum is inverse to the root of the product of four sine functions and, in the case of four polynomials, this expression additionally contains the elliptic integral K(k) as a multiplier. Analogs and particular cases are considered which allow one to compare the relationships proved in this note with results proved in various domains of mathematical physics and classical functional analysis.     

Convergence and growth of multiple Dirichlet series

This article investigates the convergence and growth of multiple Dirichlet series. The Valiron formula of Dirichlet series is extended to n-tuple Dirichlet series and an equivalence relation between the order of n-tuple Dirichlet series and its coefficients and exponents is obtained.     

On some Diophantine fourier series

We continue our study on arithmetical Fourier series by considering two Fourier series which are related to Diophantine analysis. The first one was studied by Hardy and Littlewood in connection with the classification of numbers and the second one was studied by Hartman and Wintner by Lebesgue integration theory.