Chebyshev set - Encyclopedia of Mathematics
https://encyclopediaofmath.org/wiki/Chebyshev_set04.06.2020 · The notion of a Chebyshev set is a logical development of that of a Chebyshev system. A finite-dimensional vector subspace $ L \subset C ( Q ) $ with basis $ \phi _ {1} \dots \phi _ {n} $ is a Chebyshev set (Chebyshev subspace) if and only if the functions $ \phi _ {1} \dots \phi _ {n} $ form a Chebyshev system (equivalently, satisfy the Haar condition ).
Chebyshev polynomials - Wikipedia
https://en.wikipedia.org/wiki/Chebyshev_polynomialsThe Chebyshev polynomials are two sequences of polynomials related to the cosine and sine functions, notated as () and ().They can be defined several equivalent ways; in this article the polynomials are defined by starting with trigonometric functions: . The Chebyshev polynomials of the first kind are given by () = ().Similarly, define the Chebyshev polynomials of the second …
Chebyshev filter - Wikipedia
https://en.wikipedia.org/wiki/Chebyshev_filterType I Chebyshev filters are the most common types of Chebyshev filters. The gain (or amplitude) response, (), as a function of angular frequency of the nth-order low-pass filter is equal to the absolute value of the transfer function () evaluated at =: = | | = + (/)where is the ripple factor, is the cutoff frequency and is a Chebyshev polynomial of the th order.