In this paper the author writes a simple characterization for the best copositive approximation to elements of C(Q) by elements of finite dimensional strict Chebyshev subspaces of C(Q) in the case when Q is any compac...In this paper the author writes a simple characterization for the best copositive approximation to elements of C(Q) by elements of finite dimensional strict Chebyshev subspaces of C(Q) in the case when Q is any compact subset of real numbers. At the end of the paper the author applies this result for different classes of Q.展开更多
Let f be a Maass eigenform that is a new form of level N on Γ0(N),with Laplace eigenvalue 1/4 + νf2 . Then,all its Fourier coefficients {λf(n)}∞n=1 are real,and we may normalize so that λf (1) = 1. It is proved,i...Let f be a Maass eigenform that is a new form of level N on Γ0(N),with Laplace eigenvalue 1/4 + νf2 . Then,all its Fourier coefficients {λf(n)}∞n=1 are real,and we may normalize so that λf (1) = 1. It is proved,in this paper,that the first sign change in the sequence {λf(n)}n∞=1 occurs at some n satisfying n《{(3+|νf|2)N }1/2-δ and (n,N)=1. This generalizes the previous results for holomorphic Hecke eigenforms.展开更多
This paper is part II of ＂On Copositive Approximation in Spaces of Contin- uous Functions＂. In this paper, the author shows that if Q is any compact subset of real numbers, and M is any finite dimensional strict Che...This paper is part II of ＂On Copositive Approximation in Spaces of Contin- uous Functions＂. In this paper, the author shows that if Q is any compact subset of real numbers, and M is any finite dimensional strict Chebyshev subspace of C （Q）, then for any admissible function f ∈ C（Q）／M, the best copositive approximation to f from M is unique.展开更多
We introduce the definition of q-Stancu operator and investigate its approximation and shape-preserving property. With the help of the sign changes of f（x） and Ln = f（f, q;x） the shape-preserving property of q-Sta...We introduce the definition of q-Stancu operator and investigate its approximation and shape-preserving property. With the help of the sign changes of f（x） and Ln = f（f, q;x） the shape-preserving property of q-Stancu operator is obtained.展开更多
文摘In this paper the author writes a simple characterization for the best copositive approximation to elements of C(Q) by elements of finite dimensional strict Chebyshev subspaces of C(Q) in the case when Q is any compact subset of real numbers. At the end of the paper the author applies this result for different classes of Q.
文摘Let f be a Maass eigenform that is a new form of level N on Γ0(N),with Laplace eigenvalue 1/4 + νf2 . Then,all its Fourier coefficients {λf(n)}∞n=1 are real,and we may normalize so that λf (1) = 1. It is proved,in this paper,that the first sign change in the sequence {λf(n)}n∞=1 occurs at some n satisfying n《{(3+|νf|2)N }1/2-δ and (n,N)=1. This generalizes the previous results for holomorphic Hecke eigenforms.
文摘This paper is part II of ＂On Copositive Approximation in Spaces of Contin- uous Functions＂. In this paper, the author shows that if Q is any compact subset of real numbers, and M is any finite dimensional strict Chebyshev subspace of C （Q）, then for any admissible function f ∈ C（Q）／M, the best copositive approximation to f from M is unique.
基金Supported by the Education Department of Zhejiang Province(20071078)
文摘We introduce the definition of q-Stancu operator and investigate its approximation and shape-preserving property. With the help of the sign changes of f（x） and Ln = f（f, q;x） the shape-preserving property of q-Stancu operator is obtained.
