Definition

interpolation on top of Chebyshev node

Node

The selection of node can be:

  • Chebyshev–Gauss: 𝑥𝑗=cos(𝜋2𝑗+12𝑛)
  • Chebyshev–Lobatto
  • etc

Implementation

it can be implemented by Lagrange Interpolation, orthogonal polynomial interpolation, and etc.
OR

import numpy as np
import numpy.linalg as la
 
n = len(y)
x = np.cos((2 * np.array(list(range(n))) + 1)*np.pi/(2*n))
V = np.zeros((n,n))
V[:,0] = 1
V[:,1] = x
for i in range(2, n):
    V[:,i] = 2*x*V[:,i-1] - V[:,i-2]
 
c = la.solve(V,y)

Crude Error

max|𝑓(𝑥)𝑝𝑛1(𝑥)|𝐶2𝑛1(𝑏𝑎)𝑛

where

  • 𝐶 constant
  • 𝑛 number of nodes
  • 𝑏𝑎 the range