该文研究Dirichlet及随机Dirichlet级数在水平直线或半直线上的增长性,包含关于Taylor级数的相应结果,例如下列简单结果:设Taylor级数F_(z)=sum from n=0 to ∞有收敛半径∞或1,其中0=μ_0<μ_n↑,μ_n∈N,sum from(1/μ_n)<∞....该文研究Dirichlet及随机Dirichlet级数在水平直线或半直线上的增长性,包含关于Taylor级数的相应结果,例如下列简单结果:设Taylor级数F_(z)=sum from n=0 to ∞有收敛半径∞或1,其中0=μ_0<μ_n↑,μ_n∈N,sum from(1/μ_n)<∞.如果这级数有级ρ(在收敛半径是∞或1时,“级”的意义不同),那么在第一种情形。它在从原点出发的每条射线上有级p;在第二种情形,在单位圆盘的每条射线上有级ρ．展开更多
Chaundy and Jolliffe proved that if {a n } is a non-increasing (monotonic) real sequence with lim n →∞ a n = 0, then a necessary and sufficient condition for the uniform convergence of the series ∑∞ n=1 a n sin nx...Chaundy and Jolliffe proved that if {a n } is a non-increasing (monotonic) real sequence with lim n →∞ a n = 0, then a necessary and sufficient condition for the uniform convergence of the series ∑∞ n=1 a n sin nx is lim n →∞ na n = 0. We generalize (or weaken) the monotonic condition on the coefficient sequence {a n } in this classical result to the so-called mean value bounded variation condition and prove that the generalized condition cannot be weakened further. We also establish an analogue to the generalized Chaundy-Jolliffe theorem in the complex space.展开更多
In the author’s recent publications, a parametric system biorthogonal to the corresponding segment of the exponential Fourier system was unusually effective. On its basis, it was discovered that knowledge of a finite...In the author’s recent publications, a parametric system biorthogonal to the corresponding segment of the exponential Fourier system was unusually effective. On its basis, it was discovered that knowledge of a finite number of Fourier coefficients of function f from an infinite-dimensional set of elementary functions allows f to be accurately restored (the phenomenon of over-convergence). Below, parametric biorthogonal systems are constructed for classical trigonometric Fourier series, and the corresponding phenomena of over-convergence are discovered. The decisive role here was played by representing the space L2 as an orthogonal sum of two corresponding subspaces. As a result, fast parallel algorithms for reconstructing a function from its truncated trigonometric Fourier series are proposed. The presented numerical experiments confirm the high efficiency of these convergence accelerations for smooth functions. In conclusion, the main results of the work are summarized, and some prospects for the development and generalization of the proposed approaches are discussed.展开更多
文摘该文研究Dirichlet及随机Dirichlet级数在水平直线或半直线上的增长性,包含关于Taylor级数的相应结果,例如下列简单结果:设Taylor级数F_(z)=sum from n=0 to ∞有收敛半径∞或1,其中0=μ_0<μ_n↑,μ_n∈N,sum from(1/μ_n)<∞.如果这级数有级ρ(在收敛半径是∞或1时,“级”的意义不同),那么在第一种情形。它在从原点出发的每条射线上有级p;在第二种情形,在单位圆盘的每条射线上有级ρ．
基金supported by National Sciences and Engineering Research Council of CanadaNational Natural Science Foundation of China (Grant No. 10471130)
文摘Chaundy and Jolliffe proved that if {a n } is a non-increasing (monotonic) real sequence with lim n →∞ a n = 0, then a necessary and sufficient condition for the uniform convergence of the series ∑∞ n=1 a n sin nx is lim n →∞ na n = 0. We generalize (or weaken) the monotonic condition on the coefficient sequence {a n } in this classical result to the so-called mean value bounded variation condition and prove that the generalized condition cannot be weakened further. We also establish an analogue to the generalized Chaundy-Jolliffe theorem in the complex space.
文摘In the author’s recent publications, a parametric system biorthogonal to the corresponding segment of the exponential Fourier system was unusually effective. On its basis, it was discovered that knowledge of a finite number of Fourier coefficients of function f from an infinite-dimensional set of elementary functions allows f to be accurately restored (the phenomenon of over-convergence). Below, parametric biorthogonal systems are constructed for classical trigonometric Fourier series, and the corresponding phenomena of over-convergence are discovered. The decisive role here was played by representing the space L2 as an orthogonal sum of two corresponding subspaces. As a result, fast parallel algorithms for reconstructing a function from its truncated trigonometric Fourier series are proposed. The presented numerical experiments confirm the high efficiency of these convergence accelerations for smooth functions. In conclusion, the main results of the work are summarized, and some prospects for the development and generalization of the proposed approaches are discussed.
