UNIVERSITY PARK, Pa. — Nick Trefethen, professor of applied mathematics in residence at Harvard University, will present the 2025 Russell E. Marker Lectures in Mathematics, collectively titled “Numerical Rational Functions,” Feb. 17-20 in 114 McAllister Building, on the Penn State University Park campus. These free public lectures are sponsored by the Penn State Eberly College of Science.
The series includes a lecture intended for a general audience, titled “The AAA Algorithm for Rational Approximation,” at 6 p.m. on Monday, Feb. 17, as well as more-specialized lectures: “Best, Near-Best, and Potential Theory” at 11 a.m. on Tuesday, Feb. 18; “Analytic Continuation and the One-Wavelength Principle” at 2:30 p.m. on Wednesday, Feb. 19; and “From Rational Approximation to Helmholtz Scattering” at 3:30 p.m. on Thursday, Feb. 20.
“The AAA Algorithm for Rational Approximation”
With the introduction of the AAA algorithm in 2018, the computation of rational approximations changed from a hard problem to an easy one. Trefethen and his colleagues been exploring the implications of that transformation ever since. This talk will review the algorithm and then present demonstrations of applications in various areas including interpolation of missing data, analytic continuation, function extension, analysis of solutions of dynamical systems, model order reduction, nonlinear eigenvalues, and numerical computation of the Schwarz function.
About the speaker
Nick Trefethen is professor of applied mathematics in residence at Harvard University; from 1997 to 2023 he was professor of numerical analysis and head of the Numerical Analysis Group at the University of Oxford. He was educated at Harvard and Stanford Universities and has held positions at New York University, the Massachusetts Institute of Techology and Cornell University.
Trefethen is a fellow of the Royal Society, a member of the U.S. National Academy of Engineering, and a foreign member of the Chinese Academy of Sciences, and he served from 2011 to 2012 as president of the Society for Industrial and Applied Mathematics. He has won awards including the Gold Medal of the Institute for Mathematics and its Applications, the Naylor Prize of the London Mathematical Society, and the Polya and von Neumann Prizes from SIAM. He also holds honorary doctorates from the University of Fribourg and Stellenbosch University.
As an author, Trefethen is known for his books including “Numerical Linear Algebra” (1997), “Spectral Methods in MATLAB” (2000), “Spectra and Pseudospectra” (2005), “Approximation Theory and Approximation Practice” (2013/2019), “Exploring ODEs” (2018), and “An Applied Mathematician's Apology” (2022). He organized the SIAM 100-Dollar, 100-Digit Challenge in 2002 and is the inventor of the software package Chebfun and co-inventor of the AAA algorithm for rational approximation.
About the Marker Lectures
The Marker Lectures were established in 1984 through a gift from the late Russell Earl Marker, professor emeritus of organic chemistry at Penn State, whose pioneering synthetic methods revolutionized the steroid hormone industry and opened the door to the current era of hormone therapies, including the birth control pill.
The Marker endowment allows the Penn State Eberly College of Science to present annual Marker Lectures in astronomy and astrophysics, the chemical sciences, evolutionary biology, genetic engineering, the mathematical sciences, and the physical sciences.