Chapter 5: Orthogonal Collocation and Pseudospectral Foundations
From Gaussian quadrature to Legendre pseudospectral transcription
Low-order collocation is local and transparent, but smooth trajectories can be represented far more efficiently with global polynomials. This chapter builds the required approximation theory in layers: orthogonal collocation, Legendre polynomials, Lagrange interpolation, Gaussian quadrature, and differentiation matrices. Those ingredients then lead naturally to the LGL, LG, and LGR pseudospectral schemes.