On a Class of Generalized Sampling Functions

In this note, we discuss a class of so-called generalized sampling functions. These functions are defined to be the inverse Fourier transform of a family of piecewise constant functions that are either square integrable or Lebegue integrable on the real number line. They are in fact the generalization of the classic sinc function. Two approaches of constructing the generalized sampling functions are reviewed. Their properties such as cardinality, orthogonality, and decaying properties are discussed. The interactions of those functions and Hilbert transformer are also discussed.     

On the Convergence of Sequences of Rational Approximations to Analytic Functions of a Certain Class

Complex analytic methods based on the theory of Walsh (1935)and on properties of orthonormal polynomials with general weight-functionon [–1, 1] are applied to the construction of variousrational approximations on the interval [–k, k] to a functiong(x) defined by or by where Remainder estimates are obtained, and from these, in the caseswhere g(x) is real on [–k, k], an asymptotic formula isobtained for the maximum error of the best rational approximationin the sense of the uniform norm. It is also shown that therate of convergence of the sequence of best approximations ofdegree n is twice the minimum rate predicted by Walsh's theory,in the sense that the degree of the approximation required fora given precision is approximately only half as great. Graphs are shown which illustrate that, for a simple example,the remainder estimates on which this asymptotic formula isbased are remarkably accurate even for approximations of lowdegree.     

Entire Approximations for a Class of Truncated and Odd Functions

We solve the problem of finding optimal entire approximations of prescribed exponential type (unrestricted, majorant and minorant) for a class of truncated and odd functions with a shifted exponential subordination, minimizing the $L^{1}(\mathbb {R})$ -error. The class considered here includes new examples such as the truncated logarithm and truncated shifted power functions. This paper is the counterpart of the works (Carneiro and Vaaler in Trans. Am. Math. Soc. 362:5803–5843, 2010) and (Carneiro and Vaaler in Constr. Approx. 31(2):259–288, 2010) where the analogous problem for even functions was treated.     

Toward a Unified Theory of Generalized Functions: Convergence

Generalized functions are usually treated as bounded linear functionals on spaces of test functions. Here they are considered as objects which ?convolute”? with test functions and satisfy a certain associativity condition. In this setting simple definitions are given for convergence of sequences of test functions and generalized functions, definitions which do not depend on particular properties of the space of test functions. It is shown that for the most commonly used spaces, these general definitions reduce to the standard ones.     

一类广义拟牛顿算法的收敛性

本文提出一类广义拟牛顿算法,新类算法降低了关于目标函数的假设条件,将线搜索扩展 到一般形式,它概括了若干种常用的非精确线搜索技术.此外,算法对迭代校正公式中的参数Φk的 选取范围做了较大扩展(可以取负值).     

On the Representation of Approximate Subdifferentials for a Class of Generalized Convex Functions

Given a family of real-valued functions defined in a normed vector space X, we study a class of -convex functions having a simpler representation for the --subdifferential. The case =X^* with X being a Banach space (the Fenchel case) is particularly analysed, and we find that the sublinear lower semicontinuous functions satisfy the simpler representation with respect to X^*. As a side result, we provide various new subdifferential-type charaterizations of positively homogeneous functions among those which are lower semicontinuous and convex. In addition, we also discuss that family related to the the so-called prox-bounded functions. In this more general framework our simpler representation may give rise to a new notion of enlargement of the subdifferential.Mathematics Subject Classifications (2000) 47H05, 46B99, 47H17.This work is based on research material supported in part by CONICYT-Chile through FONDECYT 101-0116 and FONDAP-Matemáticas Aplicadas II.     

On a Class of Generalized Lacunary Difference Sequence Spaces Defined by Orlicz Functions

In this article we introduce the generalized lacunary difference sequence spaces [N_θ,M,Δ~m]_0,[N_θ,M,Δ~m]_1 and [N_θ,M,Δ~m]_∞using m~(th)- difference.We study their properties like completeness,solidness,symmetricity.Also we obtain some inclusion relations involving the spaces [N_θ,M,Δ~m]_0,[N_θ,M,Δ~m]_1 and[N_θ,M,Δ~m]_∞and the Cesàro summable and strongly Cesàro summable sequences.     

The Weierstrass Transform for a Class of Generalized Functions

The classical theory of the Weierstrass transform is extended to a generalized function space which is the dual of a testing function space consisting of purely entire functions with certain growth conditions developed by Kenneth B. Howell. An inversion formula and characterizations for this transform are obtained. A comparative study with the existing literature is also undertaken.     

On a Class of Generalized Integrands

Abstract

In the framework of the theory of stochastic integration with respect to a family of semimartingales depending on a continuous parameter, introduced by De Donno and Pratelli as a mathematical background to the theory of bond markets, we analyze a special class of integrands that preserve some nice properties of the finite-dimensional stochastic integral. In particular, we focus our attention on the class of processes considered by Mikulevicius and Rozovskii for the case of a locally square integrable cylindrical martingale and which includes an appropriate set of measure-valued processes.     

Abscissa of Absolute Convergence of a Class of Generalized Euler Products

Mathematical Notes -     

Properties of Convergence for a Class of Generalized $q$-Gamma Operators.

In this paper, a generalization of $q$-Gamma operators based on the concept of $q$-integer is introduced. We investigate the moments and central moments of the operators by computation, obtain a local approximation theorem and get the pointwise convergence rate theorem and also obtain a weighted approximation theorem. Finally, a Voronovskaya type asymptotic formula was given.     

一类整函数的牛顿法的拟直接盘和直接盘

In this paper, we consider Newton＇s method for a class of entire functions with infinite order. By using theory of dynamics of functions meromorphic outside a small set, we find there are some series of virtual immediate basins in which the dynamics converges to infinity and a series of immediate basins with finite area in the Fatou sets of Newton＇s method.     

关于一类单叶函数

A sharp coefficient estimate,distortion theorem and the radius of convexityare determined for the class R(α,β,A,B) of function f(z)=z+(?)a_nzⁿ satisfyingthe condition |(f′(z)-1)/(Bf′(z)-[B+(A-B)(1-α)])|<β for some α,β(0≤α<1,0<β≤1) and -1≤A相似文献   

Some Orders and Types of Generalized Hadamard Product of Entire Functions

In this paper we introduce an estimation, namely, the upper bounds of the order and type, logarithmic order and logarithmic type and q-order and q-type of generalized Hadamard product of functions of the complex variables z. We append this study by getting a result concerning the subject of linear substitution.     

On a Class of Integer-Valued Functions

The paper deals with the class of entire functions that increase not faster than exp{γ∣z∣^6/5(ln∣z∣)^?1} and that, together with their first derivatives, take values from a fixed field of algebraic numbers at the points of a two-dimensional lattice of general form (in this case, the values increase not too fast). It is shown that any such functions is either a polynomial or can be represented in the form e^?mαzP(e^αz), where m is a nonnegative integer, P is a polynomial, and α is an algebraic number.

     

On the Growth of Composite Entire Functions

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On a Generalized Class of Minimax Inequalities

Some results on a generalized class of minimax inequalities based on the r–I–G–H-KKM mapping theorems in a G–H-space setting are presented. The r–I–G–H-KKM mappings represent a new class of KKM mappings in G–H-spaces as well as in the interval spaces.     

On the Convergence of an Interpolation Process to an Entire Operator in a Hilbert Space

For an entire operator in a Hilbert space, we consider an interpolation operator-valued polynomial that has a fairly simple structure. A theorem on pointwise convergence of the iteration process to the entire operator is proved.