In this paper best approximation by reciprocals of functions of a subspace U_n=span (u_1,…,u_n)satisfying coefficient constraints is considered.We present a characterization of best approximations.When(u_1,…,u_n)is ...In this paper best approximation by reciprocals of functions of a subspace U_n=span (u_1,…,u_n)satisfying coefficient constraints is considered.We present a characterization of best approximations.When(u_1,…,u_n)is a Descartes system an explicit characterization of best approximations by equioscillations is given.Existence and uniqueness results are shown. Moreover,the theory is applied to best approximaitons by reciprocals of polynomials.展开更多
文摘In this paper best approximation by reciprocals of functions of a subspace U_n=span (u_1,…,u_n)satisfying coefficient constraints is considered.We present a characterization of best approximations.When(u_1,…,u_n)is a Descartes system an explicit characterization of best approximations by equioscillations is given.Existence and uniqueness results are shown. Moreover,the theory is applied to best approximaitons by reciprocals of polynomials.
