Chebyshev nodes - Wikipedia
https://en.wikipedia.org/wiki/Chebyshev_nodesThe Chebyshev nodes are important in approximation theory because they form a particularly good set of nodes for polynomial interpolation. Given a function ƒ on the interval and points in that interval, the interpolation polynomial is that unique polynomial of degree at most which has value at each point . The interpolation error at is for some (depending on x) in [−1, 1]. So it is logical to try to minimize
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 ways that have the same end result; 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 kind as