1 research outputs found
Projective view at Optimization Problem for Multiband Filter
The best uniform rational approximation of the \emph{sign} function on two
intervals separated by zero was explicitly solved by E.I. Zolotar\"ev 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.Comment: 15 pages, 4 figures, minor corrections compared to V