27th Conference of the International Linear Algebra Society (ILAS 2026)

How ill conditioned can sub-matrices of the Fourier matrix be?

May 18, 2026, 4:35 PM

25m

Torgersen Hall 3100 (Virginia Tech)

Minisymposium Talk New Directions and Challenges in Linear Algebra New Directions and Challenges in Linear Algebra

Speaker

John Urschel (MIT)

Description

The discrete Fourier transform matrix, and sub-matrices of it, appear in a wide variety of applications. While the Fourier matrix itself is a scaled unitary matrix, its sub-matrices can be exponentially ill-conditioned. In this talk, we discuss applications, prior work, and we provide tight estimates for just how ill-conditioned such matrices can be.