Lloyd Nicholas Trefethen (born 30 August 1955) is an American mathematician, professor of numerical analysis and head of the Numerical Analysis Group at the Mathematical Institute, University of Oxford. Education Trefethen was born 30 August 1955 in Boston, Massachusetts, the son of mechanical engineer Lloyd M. Trefethen and codebreaker, poet, teacher and editor Florence Newman Trefethen. He obtained his bachelor's degree from Harvard University in 1977 and his master's from Stanford University in 1980. His PhD was on Wave Propagation and Stability for Finite Difference Schemes supervised by Joseph E. Oliger at Stanford University. Career and research Following his PhD, Trefethen went on to work at the Courant Institute of Mathematical Sciences in New York, Massachusetts Institute of Technology, and Cornell University, before being appointed to a chair at the University of Oxford and a Fellowship of Balliol College, Oxford. , he has published around 150 journal papers spanning a wide range of areas within numerical analysis and applied mathematics, including non-normal eigenvalue problems and applications, spectral methods for differential equations, numerical linear algebra, fluid mechanics, computational complex analysis, and approximation theory. He is perhaps best known for his work on pseudospectra of non-normal matrices and operators. This work covers theoretical aspects as well as numerical algorithms, and applications including fluid mechanics, numerical solution of partial differential equations, numerical linear algebra, shuffling of cards, random matrices, differential equations and lasers. Trefethen is currently an ISI highly cited researcher. Trefethen has written a number of books on numerical analysis including Numerical Linear Algebra with David Bau, Spectral Methods in MATLAB, Schwarz–Christoffel Mapping with Tobin Driscoll, and Spectra and Pseudospectra: The Behavior of Nonnormal Matrices and Operators with Mark Embree. He is the leader of the MATLAB-based Chebfun software project. In 2013 he proposed a new formula to calculate the BMI of a person: (International System of Units) Books Numerical Linear Algebra (SIAM, 1997) with David Bau Spectral Methods in Matlab (SIAM, 2000) Schwarz-Christoffel Mapping (Cambridge, 2002) with T. A. Driscoll Spectra and Pseudospectra: The Behavior of Nonnormal Matrices and Operators (Princeton, 2005) with Mark Embree Trefethen's Index Cards (World Scientific 2011) Approximation Theory and Approximation Practice (SIAM, 2013 and 2020) Exploring ODEs (SIAM, 2018) with Á. Birkisson and T. A. Driscoll An Applied Mathematician’s Apology (SIAM, 2022) Awards and honours Trefethen was the first winner of the Leslie Fox Prize for Numerical Analysis. In 1998 he was an Invited Speaker of