- Lecturer: Nick Trefethen

General Prerequisites:

Some experience with (a) numerical analysis and (b) complex variables would be helpful, but neither is required.

Course Term: Michaelmas

Course Lecture Information: 16 lectures

Course Weight: 1

Course Level: M

Assessment Type: Written Examination

Course Overview:

How can a function f(\(x\)) be approximated over a prescribed domain by a simpler function like a polynomial or a rational function? Such questions were at the heart of analysis in the early 1900s and later grew into a mature subject of approximation theory. Recently they have been invigorated as problems of approximation have become central to computational algorithms for differential equations, linear algebra, optimization and other fields. This course, based on Trefethen's text in which results are illustrated by Chebfun computations, will focus in a modern but still rigorous way on the fundamental results of interpolation and approximation and their algorithmic application.

Course Synopsis:

Chebyshev interpolants, polynomials, and series. Barycentric interpolation formula. Weierstrass approximation theorem. Convergence rates of polynomial approximations. Hermite integral formula and Runge phenomenon. Lebesgue constants, polynomial rootfinding. Orthogonal polynomials. Clenshaw-Curtis and Gauss quadrature. Rational approximation.