Approximation of Functions by the Szász-Mirakjan-Kantorovich Operator

We characterize the approximation of functions in the L_p-norm by the Szász-Mirakjan-Kantorovich operator. We prove a direct and a strong converse inequality of type B in terms of an appropriate K-functional.     

关于Szász-Mirakjan算子

§1 前言设 C={f∶f∈C[0,∞),存在着 N>0,使得 f(x)=O(x~N)(x→ ∞)}.C~r={f;f~(t)∈C.i=0,1,2,…,r}.Szász-Mirakjan 算子是:S_n(,fx)=(?)f(k/n)P_(nk)(x),P_(nk)(x)=e~(-nx)((nx)~k)/(k!),f∈C设 C_0={f:f∈C[0,∞),(?)(?)类似地定义 C_0~r.在[1]中我们曾证明了:对于C_0 中的函数 f,‖S_n(f)-f‖_c=O(k(f,(?)).若0<α<1,则‖S_n(f)-f‖_e=O(n~(-α)与k(f,t)=O(t~(2α))等价。这里 k(f,t)=inf{‖f-g‖_c t~2‖xg〃‖c‖}.不难类似地证明此结     

Pointwise Approximation by Szàsz-Mirakjan Quasi-Interpolants

Recently some classical operator quasi-interpolants were introduced to obtain much faster convergence. A.T. Diallo investigated some approximation properties of Szàsz-Mirakjan Quasi-Interpolants, but he obtained only direct theorem with Ditzian-Totik modulus ω2rψ(f, t). In this paper, we extend Diallo's result and solve completely the characterization on the rate of approximation by the method of quasi-interpolants to functions f ∈ CB[0, ∞) by making use of the unified modulus ω2rψλ> (f, t) (0 ≤λ≤ 1).     

On q-Parametric Szász-Mirakjan Operators

In the present paper, we introduce q-parametric Szász-Mirakjan operators. We study convergence properties of these operators S _n,q (f). We obtain inequalities for the weighted approximation error of q-Szász-Mirakjan operators. Such inequalities are valid for functions of polynomial growth and are expressed in terms of weighted moduli of continuity. We also discuss Voronovskaja-type formula for q-Szász-Mirakjan operators.     

Szász-Mirakjan算子逐点加权同时逼近

本文研究了Szász-Mirakjan算子加权同时逼近的问题.利用加权光滑模ω2φλ(f,t)u,获得了Szász-Mirakjan算子加权同时逼近的点态结果,推广了已知的结果.     

Approximation of Generalized Szasz—Mirakjan Operator

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关于多元Szász-Mirakjan算子的加权逼近

本文主要讨论一类二元Ｓｚáｓｚ－Ｍｉｒａｋｊｉａｎ算子的加权逼近问题。我们首先指出了在通常的加权范数下它是无界的。然后我们给出了一类新的加权范数，在此范数下，它是有界的。最后利用一类多元Ｋ－泛函与多元分解技巧，我们给出了二元Ｓｚａｓｚ－Ｍｉｒａｋｉａｎ算子加权逼近的特征刻划。关键词     

Degenerate differential equations and modified Szász-Mirakjan operators

We consider the elliptic operator Lu(x):= xu″(x)+β(x)u′(x) + γ (x)u(x) with Wentzell-type boundary condition, in spaces of continuous function on [0,+∞[. We prove that such operators generate positive C ₀-semigroup which can be approximated by means of iterated of modified Szász-Mirakjan operators here introduced.     

Pointwise characterization for combinations of Szász-Mirakjan operators

The purpose of this paper is to characterize the pointwise rate of convergence for the combinations of Szász-Mirakjan operators using Ditzian-Totik modulus of smoothness.     

Approximation by modified Szász-Durrmeyer operators

The main goal of this paper is to introduce Durrmeyer modifications for the generalized Szász–Mirakyan operators defined in (Aral et al., in Results Math 65:441–452, 2014). The construction of the new operators is based on a function \(\rho \) which is continuously differentiable \(\infty \) times on \( \left[ 0,\infty \right) ,\) such that \(\rho \left( 0\right) =0\) and \( \inf _{x\in \left[ 0,\infty \right) }\rho ^{\prime }\left( x\right) \ge 1.\) Involving the weighted modulus of continuity constructed using the function \( \rho \), approximation properties of the operators are explored: uniform convergence over unbounded intervals is established and a quantitative Voronovskaya theorem is given. Moreover, we obtain direct approximation properties of the operators in terms of the moduli of smoothness. Our results show that the new operators are sensitive to the rate of convergence to f,  depending on the selection of \(\rho .\) For the particular case \(\rho \left( x\right) =x\), the previous results for classical Szász-Durrmeyer operators are captured.     

关于Szász-Mirakjan型算子的加权逼近

设S_n(f;x)表示如下的Sz(?)sz-Mirakjan算子:S_n(f;x)=sum from k=0 to ∞ f(k/n)S_(nk)(x),这里S_(nk)(x)=e~(-nx)(nx)~k/k!,x∈[0,∞),f∈C_[0,∞),C_[0,∞),表示在[0,∞)上连续且有界之函数集,1983年在[1]中给出了Sn(f;x)在一致逼近意义下的特征刻划,为讨论L_p逼近,[2]中引进了如下的Sz(?)sz-Mirakjan-Kantorovich算子:     

关于Szász-Mirakjan型算子的加权逼近

设S_n(f;x)表示如下的Sz(?)sz-Mirakjan算子:S_n(f;x)=sum from k=0 to ∞ f(k/n)S_(nk)(x),这里S_(nk)(x)=e~(-nx)(nx)~k/k!,x∈[0,∞),f∈C_[0,∞),C_[0,∞),表示在[0,∞)上连续且有界之函数集,1983年在[1]中给出了Sn(f;x)在一致逼近意义下的特征刻划,为讨论L_p逼近,[2]中引进了如下的Sz(?)sz-Mirakjan-Kantorovich算子:     

Pointwise characterization for combinations of Szász-Mirakjan operators

The purpose of this paper is to characterize the pointwise rate of convergence for the combinations of Szász-Mirakjan operators using Ditzian-Totik modulus of smoothness.     

Direct Result for a Summation-Integral Type Modification of Szász-Mirakjan Operators

In this paper, study of direct result for a summation-integral type modification of Szász-Mirakjan operators is carried out. Calculation of moments, density result and a Voronovskaja-type result are also obtained.     

On the Generalized Szász–Mirakyan Operators

In this paper, we construct sequences of Szász–Mirakyan operators which are based on a function ρ. This function not only characterizes the operators but also characterizes the Korovkin set ${\left \{ 1,\rho ,\rho ^{2} \right \}}$ in a weighted function space. We give theorems about convergence of these operators to the identity operator on weighted spaces which are constructed using the function ρ and which are subspaces of the space of continuous functions on ${\mathbb{R} ^{+}}$ . We give quantitative type theorems in order to obtain the degree of weighted convergence with the help of a weighted modulus of continuity constructed using the function ρ. Further, we prove some shape-preserving properties of the operators such as the ρ-convexity and the monotonicity. Our results generalize the corresponding ones for the classical Szász operators.     

Szász-Mirakjan算子线性组合和导数的点态逼近定理

本文给出了Szász-Mirakjan算子线性组合的点态逼近定理。另外,还研究了Szász-Mirakjan算子高阶导数与所逼近函数光滑性之间的关系。     

Approximation by the Complex form of a Link Operator Between the Phillips and the Szász–Mirakjan Operators

Results in Mathematics - The link operator $${P_{\alpha}^\rho(f,x)=\sum_{k=1}^\infty s_{\alpha,k}(x)\int_0^\infty \theta_{\alpha,k}^\rho(t)f(t)dt+e^{-\alpha x}f(0)}$$ , $${\alpha, \rho &gt;...     

Quantitative Estimates for Generalized Szász Operators of Max-Product Kind

We introduce a certain type generalized Szász operators of max-product kind and give an upper estimate for the error of approximation using a Shisha–Mond-type theorem.     

Approximation properties of Szász–Mirakyan operators preserving exponential functions

Positivity - This paper is a natural continuation of Acar et al. (Mediterr J Math 14:6, 2017, https://doi.org/10.1007/s00009-016-0804-7 ) where Szász–Mirakyan operators preserving...