Figure 7

Figure 7: Function f = cos3(πx ∕2) + (x + 1)3∕8 (black curve) and its interpolant IN f on Chebyshev polynomials (red curve), for N = 4 (left panel) and N = 6 (right panel). The collocation points are denoted by the blue circles and correspond to Gauss–Lobatto quadrature.