
arXiv: 1912.00197
The best uniform rational approximation of the \emph{sign} function on two intervals separated by zero was explicitly solved by E.I. Zolotarëv in 1877. This optimization problem is the initial step in the staircase of the so called approximation problems for multiband filters which are of great importance for electrical engineering. We show that known in the literature optimality criterion for this problem may be contradictory since it does not take into account the projective invariance of the problem. We propose a new consistently projective formulation of this problem and give a constructive optimality criterion for it.
15 pages, 4 figures, minor corrections compared to V1
equiripple property, Circuits in qualitative investigation and simulation of models, Stiefel class, Systems and Control (eess.SY), Electrical Engineering and Systems Science - Systems and Control, alternation, Best approximation, Chebyshev systems, Approximation by rational functions, Optimality conditions for minimax problems, optimization of electrical filters, FOS: Electrical engineering, electronic engineering, information engineering, uniform rational approximation, ansatz method
equiripple property, Circuits in qualitative investigation and simulation of models, Stiefel class, Systems and Control (eess.SY), Electrical Engineering and Systems Science - Systems and Control, alternation, Best approximation, Chebyshev systems, Approximation by rational functions, Optimality conditions for minimax problems, optimization of electrical filters, FOS: Electrical engineering, electronic engineering, information engineering, uniform rational approximation, ansatz method
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 1 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Average | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
