10 papers
LU Factorization of Discrete Random Matrices
Samuel Orellana Mateo, John Urschel, Nicholas West
We consider the probability that a discrete random matrix is \emph{strongly non-singular}, meaning all its leading principal submatrices are non-singular. This property is…
What is Jackson's constant?
Rikhav Shah, John Urschel, Nicholas West
We prove a refinement of Jackson's theorem on the approximation of Lipschitz functions by trigonometric polynomials. Our result precisely characterizes the leading error term assoc…
Spectral density estimation for normal matrices
Cameron Musco, Christopher Musco, Rikhav Shah +2
The spectral density estimation problem asks for an algorithm that, given an matrix , outputs a probability measure that is a good approximation to the uniform distr…
On the exponential rate of the condition number of Fourier submatrices and Vandermonde matrices
Rikhav Shah, John Urschel
The discrete Fourier transform matrix is one of the most important matrices in linear algebra, and submatrices of it arise in a variety of applications. Though the discrete Fourier…
The largest 5th pivot may be the root of a 61st degree polynomial
James Chen, Alan Edelman, John Urschel
This paper introduces a number of new techniques in the study of the famous question from numerical linear algebra: what is the largest possible growth factor when performing Gauss…
On the Maximum Spread of Non-Negative Matrices
Susie Lu, John Urschel
Given a directed graph , the spread of is the largest distance between any two eigenvalues of its adjacency matrix. In 2022, Breen, Riasanovsky, Tait, and Urschel asked what…