Chebyshev polynomials Definition and 12 Threads

  1. G

    A Coefficients of Chebyshev polynomials

    Not long ago, I derived the formula for Chebyshev polynomials $$T_{n}\left( x\right)= \sum_{k=0}^{\lfloor \frac{n}{2} \rfloor}{n \choose 2k}x^{n-2k}\left( x^2-1\right)^{k}$$ How to extract the coefficients of this polynomial of degree n ? I tried using Newton's binomial but got a double sum...
  2. U

    I Finding a limit involving Chebyshev polynomials

    How could I show that this limit: ##\lim_{N\to\infty}\frac{\sum_{p=1}^N T_{4N} \left(u_0(N)\cdot \cos\frac{p\pi}{2N+1}\right)}{N}## is equal to 0? In the expression above ##T_{4N}## is the Chebyshev polynomials of order ##4N##, ##u_0(N)\geq 1## is a number such that ##T_{4N}(u_0)=b##, with...
  3. C

    I Question about weights using Chebyshev polynomials as quadrature

    Hello everyone. I am studying this article since I am interested in optimization. The article makes use of Clenshaw–Curtis quadrature scheme to discretize the integral part of the cost function to a finite sum using Chebyshev polynomials. The article differentiates between the case of odd...
  4. C

    I Question about the roots of Chebyshev polynomials

    Hello everyone. I am trying to construct an optimization problem using Chebyshev pseudospectral method as described in this article. For that, I need to calculate the zeros of the Chebyshev polynomial of any order. In the article is sugested to do it as tk=cos(πk/N) k=0, ..., N...
  5. C

    Python How can I evaluate a Chebishev polynomial in python?

    Hello everyone. I need to construct in python a function which returns the evaluation of a Chebishev polynomial of order k evaluated in x. I have tested the function chebval form these documents, but it doesn't provide what I look for, since I have tested the third one, 4t^3-3t and import numpy...
  6. M

    MHB Identities of Chebyshev polynomials

    Hey! :o We are given the polynomial functions $$T_0(x)=1, T_1(x)=x, x \in \mathbb{R} \\ T_{n+1}(x)=2xT_n(x)-T_{n-1}(x), n \in \mathbb{N}, x \in \mathbb{R}$$ (Chebyshev polynomials) Using induction I have to show that: the degree of $T_n$ is $n$ $\forall n \in \mathbb{N}$ : $T_n(1)=1$...
  7. M

    What is the Solution to the Chebyshev Polynomial Problem?

    This is something Chebyshev polynomial problems. I need to show that: ##\sum_{r=0}^{n}T_{2r}(x)=\frac{1}{2}\big ( 1+\frac{U_{2n+1}(x)}{\sqrt{1-x^2}}\big )## by using two type of solution : ##T_n(x)=\cos(n \cos^{-1}x)## and ##U_n(x)=\sin(n \cos^{-1}x)## with ##x=\cos\theta##, I have form the...
  8. C

    Need help understanding Remez Algorithm and Chebyshev Polynomials

    So I've been reading about minimax polynomial approximations and have found them to be pretty impressive. However, i am confused on exactly how to determine the constants. The first step is supposed be solving for the Chebyshev polynomials as an initial guess. I'm reading wikipedia but I'm a...
  9. M

    Question on Chebyshev polynomials?

    Question A Chebyshev polynomial is Tn(x) = cos(arccos^(-1)(x)) My questions are: 1. what are the domain(s) and range(s) of this function? 2. Give equivalent polynomial definitions for Tn(x) when n = 0; 1; 2; 3. That is: show that the definition for Tn above really is a polynomial...
  10. W

    Anyone have any suggestions on books on chebyshev polynomials?

    i find that chebyshev polynomials are quite useful in numerical computations is there any good references?
  11. W

    Multi-dimensional Chebyshev polynomials?

    I was hoping someone could point me in the direction of a suitable extension of Chebyshev polynomials to mutple dimensions? I find Chebyshev polynomials useful in situations when I need to fit some function in a general way, imposing as little pre-concieved ideas about the form as possible...
  12. T

    A property of Chebyshev polynomials

    Hi, I fail finding a proof (even in MathWorld, in my Mathematic dictionary or on the Web) for the following property of Chebyshev polynomials: (T_i o T_j)(x) = (T_j o T_i)(x) = T_ij(x) when x is in ] -inf ; + inf [ Example : T_2(x) = 2x^2-1 T_3(x) = 4x^3-3x T_3(T_2(x)) = T_2(T_3(x)) =...
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