共查询到10条相似文献,搜索用时 93 毫秒
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本文讨论了变阶可解逼近族的插值逼近和带权逼近(权在插值点集Z上趋于无穷而在Z外为1)的关系.指出对变阶可解族而言,当逼近解为非亏损时,稠密性假设是自然满足的,且此时的最佳插值逼近等于该带权最佳逼近的极限. 相似文献
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Ana-Maria Acu 《Positivity》2017,21(1):283-297
In this paper some representations of a linear positive functional are established. These results are extended for linear positive operators \(L_n:C[a,b] \rightarrow C[a,b]\). Also, approximation properties of linear positive operators, expressed in terms of moduli of smoothness, are considered. In the last section, the remainder term in various approximation processes is studied. 相似文献
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In this note,we develop,without assuming the Haar condition,a generalized simultaneousChebyshev approximation theory which is similar to the classical Chebyshev theory and con-rains it as a special case.Our results also contain those in[1]and[3]as a special case,and thetwo conjectures proposed by C.B.Dunham in[2]are proved to be true in the case of simulta-neous approximation. 相似文献
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Gisbert Wüstholz 《manuscripta mathematica》1977,20(4):335-354
In this note we shall carry on further the simultaneous approximation of a, b and exp(bloga). In a recent paper BUNDSCHUH [2] proved a theorem which appears to be a sharpening of a theorem of SCHNEIDER [10]. But there is an error in the proof. We shall show, that under a supplementary condition, the theorem of BUNDSCHUH remains valid and as well, get an improvement to this theorem. We further give some results on linear forms in logarithms of two U-numbers with algebraic coefficients. 相似文献
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We improve over a sufficient condition given in [8] for uniqueness of a nondegenerate critical point in best rational approximation
of prescribed degree over the conjugate-symmetric Hardy space of the complement of the disk. The improved condition connects to error estimates in AAK approximation, and is necessary
and sufficient when the function to be approximated is of Markov type. For Markov functions whose defining measure satisfies
the Szego condition, we combine what precedes with sharp asymptotics in multipoint Padé approximation from [43], [40] in order
to prove uniqueness of a critical point when the degree of the approximant goes large. This lends perspective to the uniqueness
issue for more general classes of functions defined through Cauchy integrals. 相似文献
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正指数超线性Emden-Fowler方程奇异边值问题的正解 总被引:12,自引:0,他引:12
本文利用函数逼近和不动点理论给出了正指数超线性Emden-Fowler方程奇异边值问题有C1[0,1]正解的充分必要条件. 相似文献
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既是[a,b]-覆盖又是[a,b]-消去的图称为[a,b]-对等图.本文研究了最小度和[a,b]-对等图之间的关系,给出了一个图是[a,b]-对等图的关于最小度的充分条件. 相似文献